Re: [linux-dell-laptops] Re: What harddrive in Inspiron 8000?u
- Honestly, I don't think the difference between ATA100 and ATA66 is going
to make any noticeable difference. Assuming the two drives spin at
the same 4,200 RPM, and that they both have a 2 MB cache, then the difference
is that the ATA100 drive will theoretically empty the 2MB cache 1/50th of
a second, while the ATA66 drive will take 1/33rd of a second to do the
same. After that, they will both operate at the same transfer rate.
1/33 = 3/100, 1/50 = 2/100, so we are talking about 1/100 of a second
maximum possible improvement, during the first 2 MB of the data transfer.
And that assumes the data was in the cache to begin with. Actually,
this is a simplification, and you might periodically gain another 1/100
of a second, but that means that overall, if you transferred 1 GB, and
gained 1/100 sec every 2 MB, then you would gain about 5 seconds for
1 GB, which would take about 60-65 seconds to transfer at 16 MB/sec.
It just isn't a tremendous gain at all, and in the real world you
will likely see much less actual improvement than that.
This is not to say that you should not get the ATA100 disk if
you paid for it, it is just to say that in that case you are
paying extra for very little (or no) gain.
Theoretically, higher density platters and a faster rotation speed
would have a bigger impact on disk performance. Thus, the ATA66
32 GB IBM Travelstart 32GH (5400RPM, higher density) should theoretically
have noticeably greater performance than a 20 GB ATA100 disk rotating
at 4200 RPM. However, when I asked somebody to tell me what hdparm
was giving for that drive on an Inspiron 8000, it was about 16 MB
sec, or about the same as my theoretically slower 20 GB disk.
For what it is worth, I have a Hitachi DK23BA-20, which is also
a ATA66 drive. /sbin/hdparm shows it as being in UDMA4 mode,
which is ATA66, and indicates about 16 MB/sec transfer rate.
Anybody care to post some numbers for a ATA100 laptop drive?
> I just bought an i8k 3 weeks ago, and I bought it with an 20GB ATA66--
> disk, which is the same as you apparently have, namely the:
> Hitachi DB23BA-20
> When I test it with hdparm I get a throughput of 16MB/sec, which
> corresponds to an ATA66 disk.
> --- In linux-dell-laptops@y..., fredrik@w... wrote:
> > Hi,
> > I want to know what harddrive you have you in your Inspiron 8000. I
> > was supposed to get a 20 GB "ATA/100" but when I got mine it was
> > a "Hitachi DB23BA-20" which not is an "ATA/100" according to the
> > specifications Hitachi and DELL have on the websites.
> > So, I called DELL again and they said I should have a IBM harddrive
> > instead -- but, again, I went through the IBM harddrives and they
> > doesn't seem to have an "ATA/100" hd for laptops.
> > I think I would have got the same harddrive even if I had not paid
> > extra for the "ATA/100" (the standard hd in Inspiron 8K is "ATA/66").
> > Probably doesn't DELL know what "ATA/xx" means (see table below). :-)
> > Therefore I need input from you that have a so called "ATA/66" 20GB
> > what name of the harddrive you have got.
> > Thanks!
> > Fredrik
> > In common parlance, drives that use Ultra DMA are often called "Ultra
> > ATA/xx" where "xx" is the speed of the interface. So, few people
> > really talk about current drives being "Ultra DMA mode 5", they say
> > they are "Ultra ATA/100":
> > U-DMA Mode, Cycle Time (ns), Max transfer rate (MB/s), Standard, ATAxx
> > Mode 0, 240, 16.7, ATA/ATAPI-4
> > Mode 1, 160, 25.0, ATA/ATAPI-4
> > Mode 2, 120, 33.3, ATA/ATAPI-4
> > Mode 3, 90, 44.4, ATA/ATAPI-5
> > Mode 4, 60, 66.7, ATA/ATAPI-5, "ATA/66"
> > Mode 5, 40, 100.0, ATA/ATAPI-6?, "ATA/100"
> > Links:
> > Dell hd: http://support.euro.dell.com/docs/index.asp?cc=7&ct=28
> > IBM hd: http://www.storage.ibm.com/techsup/hddtech/table.htm
> > T13 (IDE/ATA standards): http://www.t13.org
> > Ultra DMA Modes: http://www.pcguide.com/ref/hdd/if/ide/modes_UDMA.htm
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