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Re: Backing Up Image Files

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  • Rick Wiggins
    Hey guys, Food for thought. I think MTBF for hard drives is in the order of 5 years. I think MTBF for Gold quality DVDs is in the order of 100 years. If you
    Message 1 of 23 , Nov 6, 2008
      Hey guys,
      Food for thought.
      I think MTBF for hard drives is in the order of 5 years.
      I think MTBF for Gold quality DVDs is in the order of 100 years.

      If you have data on two or three HDs, how long before all fail?
      If you have data on 2 or 3 DVDs, how long before they all fail?

      In addition, you may run out of room on your HDs.

      I am currently storing my data on two HDs, but have the intention of
      archiving the data on DVDs as I go through the old files and clean
      them up. I have had two hard drives fail in close temporal
      proximity. If both are connected at the same time, the danger is
      very high with electrical surges and lightning.

      I guess three would be the minimum of either configuration and that
      should be confirmed by checking the data on each repository.

      Thanks, Rick

      --- In ccd-newastro@yahoogroups.com, "Niall Saunders" <niall@...>
      wrote:
      >
      > Yes Gordon, it is a system that is too complicated for my needs as
      > well - but it does show that a system can grow out of control !!
      >
      > That said, the fundamantal principle is the HDD space is 'cheap'
      > nowadays, and if you distribute (and copy) your critical data over
      > several drives you are unlikely to really suffer if a single drive
      > fails.
      >
      > Cheers,
      > Niall Saunders
      > Clinterty Observatories
      > Aberdeen, SCOTLAND
      >
      > --- In ccd-newastro@yahoogroups.com, "mandellgl" <gmandell@> wrote:
      > >
      > > Hi Niall,
      > >
      > > A very impressive system, but too complicated for my current
      > > knowledge base. I think I will stick with 2 HDDs.
      > >
      > > Gordon
      > >
      > > --- In ccd-newastro@yahoogroups.com, "Niall Saunders" <niall@>
      > > wrote:
      > > >
      > > > Hi Gordon,
      > > >
      > > > Yep, that's all I do nowadays. CDs and DVDs, like Floppy
      Disks,
      > > > are 'passé'.
      > > >
      > > > I use a three-HDD setup, in a 'Grandfather, Father, Son' mode.
      I
      > > have a
      > > > small self-written EXE file that moves everything that changes
      > > > the 'name' of 'parent' directory on the 'Grandfather' HDD -
      > > > to 'Backup_name'. Then it copies the entire directory from
      > > the 'Father'
      > > > HDD over to the 'Grandfather' HDD. Then it copies everything
      from
      > > > the 'Son' HDD over to the 'Father' HDD.
      > > >
      > > > If ANY error is encountered, the process aborts - because no
      data
      > > has
      > > > actually been deleted at this stage, no data can have been
      lost.
      > > Even a
      > > > total failure of TWO hard drives should not result in data
      loss
      > > (sure,
      > > > there would be a lot of cursing by me, but only for a short
      > while).
      > > >
      > > > Assuming NO errors, the original data is deleted from
      > > the 'Grandfather'
      > > > and 'Father' HDDs.
      > > >
      > > > This process is scheduled to happen, automatically, any time
      the
      > PC
      > > > finds itself switched on at 3am.
      > > >
      > > > All files in a backed-up directory tree are MD5-checksummed
      for
      > the
      > > > Grandfather and Father drives, and a database of those
      checksum
      > > values
      > > > is maintained in the root directory of each HDD. The Date and
      > Time
      > > > values for any file comparison are ignored - only the file
      name,
      > > and
      > > > its directory path are used to identify a file (along with the
      > > unique
      > > > MD5 checksum). The two MD5 values of the text-based datafiles
      are
      > > also
      > > > then compared.
      > > >
      > > > Data is only transferred when needed, based on the entries in
      the
      > > > database files.
      > > >
      > > > I am currently using three 360Gb SATA drives, but am only
      running
      > > at
      > > > half capacity, or so.
      > > >
      > > > If I run out of capacity, I think that I would be more tempted
      to
      > > add
      > > > more HDD units (or larger ones) rather than trust my data to
      > CD/DVD
      > > > media. More than 40% of my archived optical media is now
      > > unreadable -
      > > > although, fortunately, I made two copies of every CD or DVD at
      > the
      > > > time, and it is usually different areas of each disc that get
      > > corrupted.
      > > >
      > > > Only in a feww cases (due to my puppies sharp little teeth !!)
      > have
      > > I
      > > > lost ENTIRE optical discs - and that was when I decided to
      start
      > > > purchasing external drives.
      > > >
      > > > Apart from the triple-drive setup (which is actually an
      INTERNAL
      > > array,
      > > > JBOD-style, in my Core-Quad, 4x2.83GHz, Vista-64, 8Gb RAM) I
      also
      > > have
      > > > 360Gb in one on-line internet-accessible NAS, 120Gb in a
      second
      > > > internal-only NAS, an 80Gb ultra-portable 2.5" drive, and an
      80Gb
      > > and a
      > > > 160Gb USB external drive.
      > > >
      > > > Add to that three 4Gb and one 8Gb flash-drive USB stick, two
      RAID-
      > 1
      > > > 80Gb drives in this notebook PC, a 60Gb and a 120Gb HDD in
      each
      > of
      > > two
      > > > other notebooks, and 120Gb in a Linux Netbook, and I really
      begin
      > > to
      > > > wonder what the h3ll all these drives actually contain !!!!
      > > >
      > > > In reality they mostly all contain CCD images that are too
      poor
      > in
      > > > quality to even waste time STORING, far less processing !!!
      > > >
      > > > I'm sure that your two-drive method will be more than reliable
      > > enough.
      > > >
      > > > Cheers,
      > > > Niall Saunders
      > > > Clinterty Observatories
      > > > Aberdeen, SCOTLAND
      > > >
      > > >
      > > > --- In ccd-newastro@yahoogroups.com, "mandellgl" <gmandell@>
      > wrote:
      > > > >
      > > > > Hi Friends.
      > > > >
      > > > > What does the group think about backing up image files on 2
      > > external
      > > > > hard drives rather than burning the data to a CD-ROM or DVD?
      > > > >
      > > > > Thanks.
      > > > >
      > > > > Gordon
      > > > >
      > > >
      > >
      >
    • Eddy
      ... have used ... Hi Don, A good alternative for Norton Save and Restore is Acronis True image . My wife has it on her laptop - I am using Norton - and it
      Message 2 of 23 , Nov 6, 2008
        --- In ccd-newastro@yahoogroups.com, "Don" <don@...> wrote:
        >
        > Ron,
        >
        > Norton Save and Restore is one such backup program for Windows. I
        have used
        > it with some reservations. It works OK but seems to be somewhat slow.
        > Right now I'm looking for a replacement for it.
        >
        > Don Waid
        >
        Hi Don,

        A good alternative for Norton Save and Restore is "Acronis True
        image". My wife has it on her laptop - I am using Norton - and it
        seems to work faster than Norton.

        Cheers,
        Eddy
      • Yahoo - Wodaski
        I haven t used any Norton products for some years now. My experience was the same: too slow, too bloated. Ron Wodaski ... [Non-text portions of this
        Message 3 of 23 , Nov 6, 2008
          I haven't used any Norton products for some years now. My experience was
          the same: too slow, too bloated. <G>

          Ron Wodaski



          Don wrote:
          > Ron,
          >
          > Norton Save and Restore is one such backup program for Windows. I have used
          > it with some reservations. It works OK but seems to be somewhat slow.
          > Right now I'm looking for a replacement for it.
          >
          > Don Waid
          >
          > ----- Original Message -----
          > From: "Yahoo - Wodaski" <yahoo@...>
          > To: <ccd-newastro@yahoogroups.com>
          > Sent: Thursday, November 06, 2008 9:53 AM
          > Subject: Re: [ccd-newastro] Re: Backing Up Image Files
          >
          >
          >
          >> RAID does have a weakness. If there is some electrical event, such as a
          >> surge, it may take out all of your hard drives.
          >>
          >> And of course one would need to set up the correct type of RAID so that
          >> data is duplicated, not spread out for speed!
          >>
          >> I've done RAID over the years, and I'm no longer such a big fan. Now
          >> that we have external hard drives that are cheap and easy to use, that
          >> is a good, maybe even better, alternative. The key is to set up backup
          >> procedures that work whether you remember or not.
          >>
          >> I like the "Time Machine" backup on the Mac - it's always going on, from
          >> hour to hour, so that you have backups almost continuously. It's like
          >> RAID in that respect. But it uses an external drive, which can be on a
          >> network (as well as USB/Firewire) and therefore as
          >> electrically/physically isolated as you need it to be.
          >>
          >> Of course, Time Machine won't help on a Windows machine, but I expect to
          >> see Windows backup products with the same frequent, incremental backup
          >> features if they aren't out there already.
          >>
          >> Ron Wodaski
          >>
          >>
          >>
          >> Roy Uyematsu wrote:
          >>
          >>> If you set up a RAID array. You can get automatic backups.
          >>>
          >>> ------------------------------------
          >>>
          >>>
          >>>
          >>>
          >>>
          >>>
          >> [Non-text portions of this message have been removed]
          >>
          >>
          >> ------------------------------------
          >>
          >>
          >>
          >>
          >>
          >
          >
          > ------------------------------------
          >
          >
          >
          >
          >


          [Non-text portions of this message have been removed]
        • Yahoo - Wodaski
          I would propose that there is no use in comparing DVD and HD. Each has something they are best at. HD is great for spontaneous duplication; DVDs are great for
          Message 4 of 23 , Nov 6, 2008
            I would propose that there is no use in comparing DVD and HD. Each has
            something they are best at. HD is great for spontaneous duplication;
            DVDs are great for archiving.

            Checking with Google, I see that HDs have MTBF on the order of 50 years.
            Not bad. Not guaranteed. And you can always step on a DVD. <G> Nothing
            is perfect. But you CAN improve your odds as soon as you make a second
            copy with whatever tool you choose.

            Ron Wodaski



            Rick Wiggins wrote:
            > Hey guys,
            > Food for thought.
            > I think MTBF for hard drives is in the order of 5 years.
            > I think MTBF for Gold quality DVDs is in the order of 100 years.
            >
            > If you have data on two or three HDs, how long before all fail?
            > If you have data on 2 or 3 DVDs, how long before they all fail?
            >
            > In addition, you may run out of room on your HDs.
            >
            > I am currently storing my data on two HDs, but have the intention of
            > archiving the data on DVDs as I go through the old files and clean
            > them up. I have had two hard drives fail in close temporal
            > proximity. If both are connected at the same time, the danger is
            > very high with electrical surges and lightning.
            >
            > I guess three would be the minimum of either configuration and that
            > should be confirmed by checking the data on each repository.
            >
            > Thanks, Rick
            >
            > --- In ccd-newastro@yahoogroups.com, "Niall Saunders" <niall@...>
            > wrote:
            >
            >> Yes Gordon, it is a system that is too complicated for my needs as
            >> well - but it does show that a system can grow out of control !!
            >>
            >> That said, the fundamantal principle is the HDD space is 'cheap'
            >> nowadays, and if you distribute (and copy) your critical data over
            >> several drives you are unlikely to really suffer if a single drive
            >> fails.
            >>
            >> Cheers,
            >> Niall Saunders
            >> Clinterty Observatories
            >> Aberdeen, SCOTLAND
            >>
            >> --- In ccd-newastro@yahoogroups.com, "mandellgl" <gmandell@> wrote:
            >>
            >>> Hi Niall,
            >>>
            >>> A very impressive system, but too complicated for my current
            >>> knowledge base. I think I will stick with 2 HDDs.
            >>>
            >>> Gordon
            >>>
            >>> --- In ccd-newastro@yahoogroups.com, "Niall Saunders" <niall@>
            >>> wrote:
            >>>
            >>>> Hi Gordon,
            >>>>
            >>>> Yep, that's all I do nowadays. CDs and DVDs, like Floppy
            >>>>
            > Disks,
            >
            >>>> are 'passé'.
            >>>>
            >>>> I use a three-HDD setup, in a 'Grandfather, Father, Son' mode.
            >>>>
            > I
            >
            >>> have a
            >>>
            >>>> small self-written EXE file that moves everything that changes
            >>>> the 'name' of 'parent' directory on the 'Grandfather' HDD -
            >>>> to 'Backup_name'. Then it copies the entire directory from
            >>>>
            >>> the 'Father'
            >>>
            >>>> HDD over to the 'Grandfather' HDD. Then it copies everything
            >>>>
            > from
            >
            >>>> the 'Son' HDD over to the 'Father' HDD.
            >>>>
            >>>> If ANY error is encountered, the process aborts - because no
            >>>>
            > data
            >
            >>> has
            >>>
            >>>> actually been deleted at this stage, no data can have been
            >>>>
            > lost.
            >
            >>> Even a
            >>>
            >>>> total failure of TWO hard drives should not result in data
            >>>>
            > loss
            >
            >>> (sure,
            >>>
            >>>> there would be a lot of cursing by me, but only for a short
            >>>>
            >> while).
            >>
            >>>> Assuming NO errors, the original data is deleted from
            >>>>
            >>> the 'Grandfather'
            >>>
            >>>> and 'Father' HDDs.
            >>>>
            >>>> This process is scheduled to happen, automatically, any time
            >>>>
            > the
            >
            >> PC
            >>
            >>>> finds itself switched on at 3am.
            >>>>
            >>>> All files in a backed-up directory tree are MD5-checksummed
            >>>>
            > for
            >
            >> the
            >>
            >>>> Grandfather and Father drives, and a database of those
            >>>>
            > checksum
            >
            >>> values
            >>>
            >>>> is maintained in the root directory of each HDD. The Date and
            >>>>
            >> Time
            >>
            >>>> values for any file comparison are ignored - only the file
            >>>>
            > name,
            >
            >>> and
            >>>
            >>>> its directory path are used to identify a file (along with the
            >>>>
            >>> unique
            >>>
            >>>> MD5 checksum). The two MD5 values of the text-based datafiles
            >>>>
            > are
            >
            >>> also
            >>>
            >>>> then compared.
            >>>>
            >>>> Data is only transferred when needed, based on the entries in
            >>>>
            > the
            >
            >>>> database files.
            >>>>
            >>>> I am currently using three 360Gb SATA drives, but am only
            >>>>
            > running
            >
            >>> at
            >>>
            >>>> half capacity, or so.
            >>>>
            >>>> If I run out of capacity, I think that I would be more tempted
            >>>>
            > to
            >
            >>> add
            >>>
            >>>> more HDD units (or larger ones) rather than trust my data to
            >>>>
            >> CD/DVD
            >>
            >>>> media. More than 40% of my archived optical media is now
            >>>>
            >>> unreadable -
            >>>
            >>>> although, fortunately, I made two copies of every CD or DVD at
            >>>>
            >> the
            >>
            >>>> time, and it is usually different areas of each disc that get
            >>>>
            >>> corrupted.
            >>>
            >>>> Only in a feww cases (due to my puppies sharp little teeth !!)
            >>>>
            >> have
            >>
            >>> I
            >>>
            >>>> lost ENTIRE optical discs - and that was when I decided to
            >>>>
            > start
            >
            >>>> purchasing external drives.
            >>>>
            >>>> Apart from the triple-drive setup (which is actually an
            >>>>
            > INTERNAL
            >
            >>> array,
            >>>
            >>>> JBOD-style, in my Core-Quad, 4x2.83GHz, Vista-64, 8Gb RAM) I
            >>>>
            > also
            >
            >>> have
            >>>
            >>>> 360Gb in one on-line internet-accessible NAS, 120Gb in a
            >>>>
            > second
            >
            >>>> internal-only NAS, an 80Gb ultra-portable 2.5" drive, and an
            >>>>
            > 80Gb
            >
            >>> and a
            >>>
            >>>> 160Gb USB external drive.
            >>>>
            >>>> Add to that three 4Gb and one 8Gb flash-drive USB stick, two
            >>>>
            > RAID-
            >
            >> 1
            >>
            >>>> 80Gb drives in this notebook PC, a 60Gb and a 120Gb HDD in
            >>>>
            > each
            >
            >> of
            >>
            >>> two
            >>>
            >>>> other notebooks, and 120Gb in a Linux Netbook, and I really
            >>>>
            > begin
            >
            >>> to
            >>>
            >>>> wonder what the h3ll all these drives actually contain !!!!
            >>>>
            >>>> In reality they mostly all contain CCD images that are too
            >>>>
            > poor
            >
            >> in
            >>
            >>>> quality to even waste time STORING, far less processing !!!
            >>>>
            >>>> I'm sure that your two-drive method will be more than reliable
            >>>>
            >>> enough.
            >>>
            >>>> Cheers,
            >>>> Niall Saunders
            >>>> Clinterty Observatories
            >>>> Aberdeen, SCOTLAND
            >>>>
            >>>>
            >>>> --- In ccd-newastro@yahoogroups.com, "mandellgl" <gmandell@>
            >>>>
            >> wrote:
            >>
            >>>>> Hi Friends.
            >>>>>
            >>>>> What does the group think about backing up image files on 2
            >>>>>
            >>> external
            >>>
            >>>>> hard drives rather than burning the data to a CD-ROM or DVD?
            >>>>>
            >>>>> Thanks.
            >>>>>
            >>>>> Gordon
            >>>>>
            >>>>>
            >
            >
            >
            > ------------------------------------
            >
            >
            >
            >
            >


            [Non-text portions of this message have been removed]
          • Mark de Regt
            I back up on two external hard drives. But the reality is that I am extremely unlikely to go to an image more than a few months old and re-process the data
            Message 5 of 23 , Nov 6, 2008
              I back up on two external hard drives.

              But the reality is that I am extremely unlikely to go to an image more than
              a few months old and re-process the data (and my final image is "archived"
              at my website, along with my computer at home), so I'm not all that
              concerned about it.

              --Mark

              > -----Original Message-----
              > From: ccd-newastro@yahoogroups.com [mailto:ccd-
              > newastro@yahoogroups.com] On Behalf Of mandellgl
              > Sent: Tuesday, November 04, 2008 4:42 PM
              > To: ccd-newastro@yahoogroups.com
              > Subject: [ccd-newastro] Backing Up Image Files
              >
              > Hi Friends.
              >
              > What does the group think about backing up image files on 2 external
              > hard drives rather than burning the data to a CD-ROM or DVD?
              >
              > Thanks.
              >
              > Gordon
              >
              >
              > ------------------------------------
              >
              >
              >
              >
              >
              > No virus found in this incoming message.
              > Checked by AVG - http://www.avg.com
              > Version: 8.0.175 / Virus Database: 270.8.5/1764 - Release Date:
              > 11/3/2008 7:46 AM
            • Mike Dodd
              ... Yes, but read this: Not encouraging, to say the least. Years ago when I actually saw hard drive spec sheets, the MTBF was
              Message 6 of 23 , Nov 6, 2008
                Yahoo - Wodaski wrote:
                > Checking with Google, I see that HDs have MTBF on the order of 50 years.
                > Not bad. Not guaranteed.

                Yes, but read this: <http://tinyurl.com/68norb> Not encouraging, to say
                the least. Years ago when I actually saw hard drive spec sheets, the
                MTBF was around 130,000 hours. The technology has improved since then,
                so I'd expect that figure to increase, and some drives now are rated for
                a million hours MTTF (mean time to failure). Not sure I believe that.

                As I understand it, a drive's life decreases with increased startups and
                shutdowns, because the heads land on (touch) the platters. A portable
                USB drive falls into this category.

                Personally, I store my astro images on a network server's drive and
                periodically copy everything over the nwtwork to a removable drive on
                another Linux computer. I also periodically burn DVDs of the astro images.
                --
                Mike

                Mike Dodd
                Montpelier, VA USA
                http://astronomy.mdodd.com
              • Frank S Barnes III
                Just one more option to add to the alternatives out there. I use a NAS (Network Attached Storage) device from Buffalo Technology. It is called a TeraStation.
                Message 7 of 23 , Nov 6, 2008
                  Just one more option to add to the alternatives out there. I use a NAS
                  (Network Attached Storage) device from Buffalo Technology. It is called
                  a TeraStation. The one I use has a terabyte of storage, is running
                  RAID5 and is powered off one of my UPSs. It connects at Gigbyte speed
                  and as far as my experience goes, it is almost as fast as my internal
                  drives on my main processing PC. It comes with a nice little backup
                  program called Memeo that takes care of automatically backing up my
                  files on the fly. Since my observatory computer is attached to my
                  network, after the nights acquisitions are finished, all my image files
                  are backed up on the NAS. I've had my first one for two years with no
                  drive failures. It sends me a report every day at 3:00 pm via email to
                  let me know the status and capacity. It also sends out emails if the
                  fan stops, or any other number of triggers you can set up. Not overly
                  expensive and they make larger storage devices as well. It comes with 2
                  USB ports and I also have 2 300Gig Maxtor drives that backup other
                  system data from other computers on the network all through the Memeo
                  software.

                  Clear Skies ......

                  Klaatu Barada Nikto ...

                  Frank S (Sandy) Barnes III
                  TwinOaks Observatory
                  http://www.skyimager.com
                  SBarnes@...
                • Al - AstroPhoto Insight
                  I had used a batch file to xcopy files from my machine to one of two USB connected hard drives. It ran via daily via scheduled backup. Now I use a Drobo
                  Message 8 of 23 , Nov 6, 2008
                    I had used a batch file to xcopy files from my machine to one of two
                    USB connected hard drives. It ran via daily via scheduled backup. Now
                    I use a Drobo instead of two separate stand alone USB drives:

                    http://drobo.com/

                    Al Degutis
                    AstroPhoto Insight Magazine
                    http://www.astrophotoinsight.com
                  • Rick Wiggins
                    Hi Ron, I did some reading and yes the MTBF is around 50 years, but of course that is average. See link:
                    Message 9 of 23 , Nov 7, 2008
                      Hi Ron,
                      I did some reading and yes the MTBF is around 50 years, but of
                      course that is average. See link:
                      http://www.storagereview.com/guide2000/ref/hdd/perf/qual/specMTBF.htm
                      l
                      Here is a true story that happened to me.
                      I was working on a project to automate manufacturing and test for a
                      major semiconductor company. All files were kept on large hard drive
                      platters on computers. We had two fully redundant computer and hard
                      drive systems to prevent disaster. The first drive crashed around
                      10:30AM, so we booted up the second system to keep the factory
                      running. We went to lunch. During lunch, lightning hit the plant and
                      took out the second unit and drive. Everone was freaked. I then told
                      my boss that I had made a third copy and kept it at home in case the
                      building burned down. Needless to say, they were very happy.

                      This just backs up your statement of make at least one copy...and
                      preferably keep the backup in a different physical location.
                      Thanks, Rick

                      --- In ccd-newastro@yahoogroups.com, Yahoo - Wodaski <yahoo@...>
                      wrote:
                      >
                      > I would propose that there is no use in comparing DVD and HD. Each
                      has
                      > something they are best at. HD is great for spontaneous
                      duplication;
                      > DVDs are great for archiving.
                      >
                      > Checking with Google, I see that HDs have MTBF on the order of 50
                      years.
                      > Not bad. Not guaranteed. And you can always step on a DVD. <G>
                      Nothing
                      > is perfect. But you CAN improve your odds as soon as you make a
                      second
                      > copy with whatever tool you choose.
                      >
                      > Ron Wodaski
                      >
                      >
                      >
                      > Rick Wiggins wrote:
                      > > Hey guys,
                      > > Food for thought.
                      > > I think MTBF for hard drives is in the order of 5 years.
                      > > I think MTBF for Gold quality DVDs is in the order of 100 years.
                      > >
                      > > If you have data on two or three HDs, how long before all fail?
                      > > If you have data on 2 or 3 DVDs, how long before they all fail?
                      > >
                      > > In addition, you may run out of room on your HDs.
                      > >
                      > > I am currently storing my data on two HDs, but have the
                      intention of
                      > > archiving the data on DVDs as I go through the old files and
                      clean
                      > > them up. I have had two hard drives fail in close temporal
                      > > proximity. If both are connected at the same time, the danger is
                      > > very high with electrical surges and lightning.
                      > >
                      > > I guess three would be the minimum of either configuration and
                      that
                      > > should be confirmed by checking the data on each repository.
                      > >
                      > > Thanks, Rick
                      > >
                      > > --- In ccd-newastro@yahoogroups.com, "Niall Saunders" <niall@>
                      > > wrote:
                      > >
                      > >> Yes Gordon, it is a system that is too complicated for my needs
                      as
                      > >> well - but it does show that a system can grow out of control !!
                      > >>
                      > >> That said, the fundamantal principle is the HDD space
                      is 'cheap'
                      > >> nowadays, and if you distribute (and copy) your critical data
                      over
                      > >> several drives you are unlikely to really suffer if a single
                      drive
                      > >> fails.
                      > >>
                      > >> Cheers,
                      > >> Niall Saunders
                      > >> Clinterty Observatories
                      > >> Aberdeen, SCOTLAND
                      > >>
                      > >> --- In ccd-newastro@yahoogroups.com, "mandellgl" <gmandell@>
                      wrote:
                      > >>
                      > >>> Hi Niall,
                      > >>>
                      > >>> A very impressive system, but too complicated for my current
                      > >>> knowledge base. I think I will stick with 2 HDDs.
                      > >>>
                      > >>> Gordon
                      > >>>
                      > >>> --- In ccd-newastro@yahoogroups.com, "Niall Saunders" <niall@>
                      > >>> wrote:
                      > >>>
                      > >>>> Hi Gordon,
                      > >>>>
                      > >>>> Yep, that's all I do nowadays. CDs and DVDs, like Floppy
                      > >>>>
                      > > Disks,
                      > >
                      > >>>> are 'passé'.
                      > >>>>
                      > >>>> I use a three-HDD setup, in a 'Grandfather, Father, Son'
                      mode.
                      > >>>>
                      > > I
                      > >
                      > >>> have a
                      > >>>
                      > >>>> small self-written EXE file that moves everything that
                      changes
                      > >>>> the 'name' of 'parent' directory on the 'Grandfather' HDD -
                      > >>>> to 'Backup_name'. Then it copies the entire directory from
                      > >>>>
                      > >>> the 'Father'
                      > >>>
                      > >>>> HDD over to the 'Grandfather' HDD. Then it copies everything
                      > >>>>
                      > > from
                      > >
                      > >>>> the 'Son' HDD over to the 'Father' HDD.
                      > >>>>
                      > >>>> If ANY error is encountered, the process aborts - because no
                      > >>>>
                      > > data
                      > >
                      > >>> has
                      > >>>
                      > >>>> actually been deleted at this stage, no data can have been
                      > >>>>
                      > > lost.
                      > >
                      > >>> Even a
                      > >>>
                      > >>>> total failure of TWO hard drives should not result in data
                      > >>>>
                      > > loss
                      > >
                      > >>> (sure,
                      > >>>
                      > >>>> there would be a lot of cursing by me, but only for a short
                      > >>>>
                      > >> while).
                      > >>
                      > >>>> Assuming NO errors, the original data is deleted from
                      > >>>>
                      > >>> the 'Grandfather'
                      > >>>
                      > >>>> and 'Father' HDDs.
                      > >>>>
                      > >>>> This process is scheduled to happen, automatically, any time
                      > >>>>
                      > > the
                      > >
                      > >> PC
                      > >>
                      > >>>> finds itself switched on at 3am.
                      > >>>>
                      > >>>> All files in a backed-up directory tree are MD5-checksummed
                      > >>>>
                      > > for
                      > >
                      > >> the
                      > >>
                      > >>>> Grandfather and Father drives, and a database of those
                      > >>>>
                      > > checksum
                      > >
                      > >>> values
                      > >>>
                      > >>>> is maintained in the root directory of each HDD. The Date and
                      > >>>>
                      > >> Time
                      > >>
                      > >>>> values for any file comparison are ignored - only the file
                      > >>>>
                      > > name,
                      > >
                      > >>> and
                      > >>>
                      > >>>> its directory path are used to identify a file (along with
                      the
                      > >>>>
                      > >>> unique
                      > >>>
                      > >>>> MD5 checksum). The two MD5 values of the text-based datafiles
                      > >>>>
                      > > are
                      > >
                      > >>> also
                      > >>>
                      > >>>> then compared.
                      > >>>>
                      > >>>> Data is only transferred when needed, based on the entries in
                      > >>>>
                      > > the
                      > >
                      > >>>> database files.
                      > >>>>
                      > >>>> I am currently using three 360Gb SATA drives, but am only
                      > >>>>
                      > > running
                      > >
                      > >>> at
                      > >>>
                      > >>>> half capacity, or so.
                      > >>>>
                      > >>>> If I run out of capacity, I think that I would be more
                      tempted
                      > >>>>
                      > > to
                      > >
                      > >>> add
                      > >>>
                      > >>>> more HDD units (or larger ones) rather than trust my data to
                      > >>>>
                      > >> CD/DVD
                      > >>
                      > >>>> media. More than 40% of my archived optical media is now
                      > >>>>
                      > >>> unreadable -
                      > >>>
                      > >>>> although, fortunately, I made two copies of every CD or DVD
                      at
                      > >>>>
                      > >> the
                      > >>
                      > >>>> time, and it is usually different areas of each disc that get
                      > >>>>
                      > >>> corrupted.
                      > >>>
                      > >>>> Only in a feww cases (due to my puppies sharp little
                      teeth !!)
                      > >>>>
                      > >> have
                      > >>
                      > >>> I
                      > >>>
                      > >>>> lost ENTIRE optical discs - and that was when I decided to
                      > >>>>
                      > > start
                      > >
                      > >>>> purchasing external drives.
                      > >>>>
                      > >>>> Apart from the triple-drive setup (which is actually an
                      > >>>>
                      > > INTERNAL
                      > >
                      > >>> array,
                      > >>>
                      > >>>> JBOD-style, in my Core-Quad, 4x2.83GHz, Vista-64, 8Gb RAM) I
                      > >>>>
                      > > also
                      > >
                      > >>> have
                      > >>>
                      > >>>> 360Gb in one on-line internet-accessible NAS, 120Gb in a
                      > >>>>
                      > > second
                      > >
                      > >>>> internal-only NAS, an 80Gb ultra-portable 2.5" drive, and an
                      > >>>>
                      > > 80Gb
                      > >
                      > >>> and a
                      > >>>
                      > >>>> 160Gb USB external drive.
                      > >>>>
                      > >>>> Add to that three 4Gb and one 8Gb flash-drive USB stick, two
                      > >>>>
                      > > RAID-
                      > >
                      > >> 1
                      > >>
                      > >>>> 80Gb drives in this notebook PC, a 60Gb and a 120Gb HDD in
                      > >>>>
                      > > each
                      > >
                      > >> of
                      > >>
                      > >>> two
                      > >>>
                      > >>>> other notebooks, and 120Gb in a Linux Netbook, and I really
                      > >>>>
                      > > begin
                      > >
                      > >>> to
                      > >>>
                      > >>>> wonder what the h3ll all these drives actually contain !!!!
                      > >>>>
                      > >>>> In reality they mostly all contain CCD images that are too
                      > >>>>
                      > > poor
                      > >
                      > >> in
                      > >>
                      > >>>> quality to even waste time STORING, far less processing !!!
                      > >>>>
                      > >>>> I'm sure that your two-drive method will be more than
                      reliable
                      > >>>>
                      > >>> enough.
                      > >>>
                      > >>>> Cheers,
                      > >>>> Niall Saunders
                      > >>>> Clinterty Observatories
                      > >>>> Aberdeen, SCOTLAND
                      > >>>>
                      > >>>>
                      > >>>> --- In ccd-newastro@yahoogroups.com, "mandellgl" <gmandell@>
                      > >>>>
                      > >> wrote:
                      > >>
                      > >>>>> Hi Friends.
                      > >>>>>
                      > >>>>> What does the group think about backing up image files on 2
                      > >>>>>
                      > >>> external
                      > >>>
                      > >>>>> hard drives rather than burning the data to a CD-ROM or DVD?
                      > >>>>>
                      > >>>>> Thanks.
                      > >>>>>
                      > >>>>> Gordon
                      > >>>>>
                      > >>>>>
                      > >
                      > >
                      > >
                      > > ------------------------------------
                      > >
                      > >
                      > >
                      > >
                      > >
                      >
                      >
                      > [Non-text portions of this message have been removed]
                      >
                    • mattreade
                      Sorry for jumping in so late. If your external drives are Seagate or Maxtor, try the free software from Seagate called DiscWizard, which can be found on their
                      Message 10 of 23 , Nov 10, 2008
                        Sorry for jumping in so late.

                        If your external drives are Seagate or Maxtor, try the free software
                        from Seagate called DiscWizard, which can be found on their download
                        page. http://www.seagate.com/www/en-us/support/downloads/

                        This is free software but does check the make of the drive is Seagate
                        or Maxtor.

                        Works great.

                        Matt R.
                      • San Diego Paul
                        ... AMEN! There is no substitute for redundancy. -Paul-
                        Message 11 of 23 , Nov 12, 2008
                          > This just backs up your statement of make at least one copy...and
                          > preferably keep the backup in a different physical location.
                          > Thanks, Rick

                          AMEN! There is no substitute for redundancy.
                          -Paul-
                        • San Diego Paul
                          Why not add another reply here? Wife & I both run companies out of our homes, and we use seperate bedrooms as our offices. In yet another bedroom (guest
                          Message 12 of 23 , Nov 12, 2008
                            Why not add another reply here? Wife & I both run companies out of
                            our homes, and we use seperate bedrooms as our offices. In yet
                            another bedroom (guest room?) I have a P4 computer built strictly out
                            of used parts leftover from other projects and customers' upgrades.
                            My total out-of-pocket on this computer was for the new hard drives.
                            I have (2) 500G Western Digital SATA drives in this computer, and it's
                            on the home LAN.

                            One HD is for my wife to backup her stuff one, and the other is mine.
                            Guess which one gets filled up faster?

                            -Paul-
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