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Isn't ext3 filesystem bad for flash

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  • Marcelino Mata
    I am just starting to use Unslung and wondering why ext3 is the default filesystem? I could not find anything on this topic in this list (or I need to search
    Message 1 of 7 , Oct 29, 2006
      I am just starting to use Unslung and wondering why ext3 is the
      default filesystem? I could not find anything on this topic in this
      list (or I need to search better) but from other Debian embedded
      devices like Familiar project, there was posting about journalling
      filesystem killing flash devices 'quickly" See here
      http://www.handhelds.org/hypermail/familiar/273/27320.html.

      Is this information not relevant anymore or do people run
      Unslung/OpenSlug etc on HD's so no one cares about this? I was
      planning on running unslung on flash drive for the rootfs and then
      using HD later for data. Before I start adding/editing the flash
      install, I figured I should have this question answered.

      Thanks,

      Marcelino
    • Laurent Gilson
      Hello, ... Because the default mode of operation is to unslung on a HD. ... No, ext3 is bad for flashs. ext2 would be better. jffs makes sense if you are
      Message 2 of 7 , Oct 30, 2006
        Hello,

        > I am just starting to use Unslung and wondering why ext3 is the
        > default filesystem?

        Because the default mode of operation is to unslung on a HD.

        > Is this information not relevant anymore

        No, ext3 is bad for flashs. ext2 would be better.

        jffs makes sense if you are working directly with flash-chips. If the
        flash is connected via USB: forget jffs & Co.

        > or do people run
        > Unslung/OpenSlug etc on HD's so no one cares about this?

        "turnup memstick" ?

        cu
      • Mike (mwester)
        The filesystem used on the internal flash is jffs2 (instead of ext3) - that avoids any problems such as the one you ve described, at least for the internal
        Message 3 of 7 , Oct 30, 2006
          The filesystem used on the internal flash is jffs2 (instead of ext3) - that
          avoids any problems such as the one you've described, at least for the
          internal flash. In terms of running ext3 on devices such as external flash
          drives, that's not such a problem since most of the external devices (if not
          all) internally "rotate" the device's "sectors" such that no one area of the
          flash is over-used (which is the fundamental problem at the heart of the
          issue). Additionally, the use of the "ext3flash" mechanism (described on
          the wiki) will ensure that Unslung does not swap on the device, nor will it
          update the date/time accessed stamps -- these two measures serve to reduce
          the write operations to the device to the point where the whole issue is
          largely mitigated.

          Mike (mwester)

          ----- Original Message -----
          From: "Marcelino Mata" <marcelino.mata@...>
          To: <nslu2-general@yahoogroups.com>
          Sent: Sunday, October 29, 2006 11:30 PM
          Subject: [nslu2-general] Isn't ext3 filesystem bad for flash


          > I am just starting to use Unslung and wondering why ext3 is the
          > default filesystem? I could not find anything on this topic in this
          > list (or I need to search better) but from other Debian embedded
          > devices like Familiar project, there was posting about journalling
          > filesystem killing flash devices 'quickly" See here
          > http://www.handhelds.org/hypermail/familiar/273/27320.html.
          >
          > Is this information not relevant anymore or do people run
          > Unslung/OpenSlug etc on HD's so no one cares about this? I was
          > planning on running unslung on flash drive for the rootfs and then
          > using HD later for data. Before I start adding/editing the flash
          > install, I figured I should have this question answered.
          >
          > Thanks,
          >
          > Marcelino
        • Craig Gates
          I recently installed unslung 6.8 on USB flashdrive and I got no indication from any documentation that installing on a flashdrive was a bad thing. In fact, it
          Message 4 of 7 , Oct 30, 2006
            I recently installed unslung 6.8 on USB flashdrive and I got no indication from any documentation that installing on a flashdrive was a bad thing. In fact, it seemed from all the documentation that this was the normal way of running unslung. When I checked my drive status (through the web gui) it said the drive was ext3 formatted.

            I'm now wondering if I should resling the slug to the HDD. What should I expect to happen if I keep unslung on the flash drive?

            Many thanks,
            Craig

            ----- Original Message ----
            From: Laurent Gilson <pumpkin@...>
            To: nslu2-general@yahoogroups.com
            Sent: Monday, October 30, 2006 8:03:15 AM
            Subject: Re: [nslu2-general] Isn't ext3 filesystem bad for flash













            Hello,



            > I am just starting to use Unslung and wondering why ext3 is the

            > default filesystem?



            Because the default mode of operation is to unslung on a HD.



            > Is this information not relevant anymore



            No, ext3 is bad for flashs. ext2 would be better.



            jffs makes sense if you are working directly with flash-chips. If the

            flash is connected via USB: forget jffs & Co.



            > or do people run

            > Unslung/OpenSlug etc on HD's so no one cares about this?



            "turnup memstick" ?



            cu












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          • Ingo Flaschberger
            ... As Laurent Gilson said, jffs2 is not useable for usb flash drives as this drives emulate a ide/scsi disk. jffs2 needs direct access to the memory chips
            Message 5 of 7 , Oct 30, 2006
              > I recently installed unslung 6.8 on USB flashdrive and I got no
              > indication from any documentation that installing on a flashdrive was a
              > bad thing. In fact, it seemed from all the documentation that this was
              > the normal way of running unslung. When I checked my drive status
              > (through the web gui) it said the drive was ext3 formatted.
              >
              > I'm now wondering if I should resling the slug to the HDD. What should
              > I expect to happen if I keep unslung on the flash drive?

              As Laurent Gilson said, jffs2 is not useable for usb flash drives as this
              drives emulate a ide/scsi disk.
              jffs2 needs direct access to the memory chips todo wearing.
              Flashdrives have wearing builtin and are seen to the os only as thumb
              block-structured logical unit.
              Thats why they are so successful. All flashdrives from various
              manufacturers have the same simple interface to the os, no need for
              special drivers, filesystems, ....

              see:
              http://en.wikipedia.org/wiki/USB_Mass_Storage_Device
              ---snip---
              The USB mass storage as such does not specify which file system shall be
              used on the device using it; instead, it mainly provides a way of reading
              out sectors as on any hard disk device. Operating systems are free to
              format this storage area with any file system they like.
              ---snap---
              ---snip---
              Note that disk file systems were not devised with flash memory in mind.
              Flash-specific concerns like limited number of writes per cell can be
              affected by a write-heavy file system, causing flash memory manufacturers
              to reserve about 5 percent of each medium's capacity for wear leveling.
              ---snap---

              http://en.wikipedia.org/wiki/Wear_leveling

              bye,
              Ingo
            • Craig Gates
              Thanks, but I m not sure if you re answering my question or commenting on the previous reply about jffs2 formatting. I currently have my NSLU2 unslung with
              Message 6 of 7 , Oct 31, 2006
                Thanks, but I'm not sure if you're answering my question or commenting on the previous reply about jffs2 formatting. I currently have my NSLU2 unslung with version 6.8 to a flashdrive (SD card in a USB reader connected to port 2). Is my safe for reliable usewith the NSLU2, or should I should I expect to have some troubles in the future because I'm using a flashdrive for unslung?
                Thanks again,
                Craig

                ----- Original Message ----
                From: Ingo Flaschberger <if@...>
                To: nslu2-general@yahoogroups.com
                Sent: Monday, October 30, 2006 11:30:55 AM
                Subject: Re: [nslu2-general] Isn't ext3 filesystem bad for flash













                > I recently installed unslung 6.8 on USB flashdrive and I got no

                > indication from any documentation that installing on a flashdrive was a

                > bad thing. In fact, it seemed from all the documentation that this was

                > the normal way of running unslung. When I checked my drive status

                > (through the web gui) it said the drive was ext3 formatted.

                >

                > I'm now wondering if I should resling the slug to the HDD. What should

                > I expect to happen if I keep unslung on the flash drive?



                As Laurent Gilson said, jffs2 is not useable for usb flash drives as this

                drives emulate a ide/scsi disk.

                jffs2 needs direct access to the memory chips todo wearing.

                Flashdrives have wearing builtin and are seen to the os only as thumb

                block-structured logical unit.

                Thats why they are so successful. All flashdrives from various

                manufacturers have the same simple interface to the os, no need for

                special drivers, filesystems, ....



                see:

                http://en.wikipedia .org/wiki/ USB_Mass_ Storage_Device

                ---snip---

                The USB mass storage as such does not specify which file system shall be

                used on the device using it; instead, it mainly provides a way of reading

                out sectors as on any hard disk device. Operating systems are free to

                format this storage area with any file system they like.

                ---snap---

                ---snip---

                Note that disk file systems were not devised with flash memory in mind.

                Flash-specific concerns like limited number of writes per cell can be

                affected by a write-heavy file system, causing flash memory manufacturers

                to reserve about 5 percent of each medium's capacity for wear leveling.

                ---snap---



                http://en.wikipedia .org/wiki/ Wear_leveling



                bye,

                Ingo












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              • Laurent Gilson
                Hello, ... unslung via turnup memstick or aht normal HD-way ? ... flashsticks should last for 5-10 years if used with the memstick-option. They fail after
                Message 7 of 7 , Nov 1 5:01 AM
                  Hello,

                  > Thanks, but I'm not sure if you're answering my question or commenting
                  > on the previous reply about jffs2 formatting. I currently have my NSLU2
                  > unslung with version 6.8 to a flashdrive (SD card in a USB reader
                  > connected to port 2).

                  unslung via "turnup memstick" or aht normal HD-way ?

                  > Is my safe for reliable usewith the NSLU2, or should I should I expect
                  > to have some troubles in the future because I'm using a flashdrive for
                  > unslung?

                  flashsticks should last for 5-10 years if used with the memstick-option.
                  They fail after 1-2 years if treated as HD.

                  cu
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