The Windows 2000/XP USB 128 GB problem
in [Storage]
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From: Svend Olaf Mikkelsen on 28 Aug 2007 16:29 On 28 Aug 2007 19:01:13 GMT, Arno Wagner <me(a)privacy.net> wrote: >Indeed. So this problem is likely the hardware issue I described earlier. > >With this Linux users could be safe, placing a partition start at >sector 268435455 seems to be the only way to trigger the problem. > >To blame for this mess are the disk manufacturers and the bridge-chip >manufacturers for being careless. > >Arno It seems as Linux aligns reads relative to the beginning of the device, so the most common partition location of all, sector 63, has the problem: dd if=/dev/sda1 of=63.bin bs=512 count=1 skip=268435392 reads sector 268435455 wrong from this Seagate disk in this USB case with the Prolific PL-2506 chip without any warning. It may be possible to make some theories about the read alignment from the previous output with bad sector in sector 268435454. -- Svend Olaf
From: Arno Wagner on 28 Aug 2007 18:27 Previously Svend Olaf Mikkelsen <svolaf(a)partitionsupport.com> wrote: > On 28 Aug 2007 19:01:13 GMT, Arno Wagner <me(a)privacy.net> wrote: >>Indeed. So this problem is likely the hardware issue I described earlier. >> >>With this Linux users could be safe, placing a partition start at >>sector 268435455 seems to be the only way to trigger the problem. >> >>To blame for this mess are the disk manufacturers and the bridge-chip >>manufacturers for being careless. >> >>Arno > It seems as Linux aligns reads relative to the beginning of the > device, Yes, that would make sense. > so the most common partition location of all, sector 63, has > the problem: > dd if=/dev/sda1 of=63.bin bs=512 count=1 skip=268435392 > reads sector 268435455 wrong from this Seagate disk in this USB case > with the Prolific PL-2506 chip without any warning. Ok, what a pity. Seems I will have to test all my external USB HDDs... > It may be possible to make some theories about the read alignment from > the previous output with bad sector in sector 268435454. Agreed. But not today. At least not for me. Arno
From: Folkert Rienstra on 29 Aug 2007 13:31
Svend Olaf Mikkelsen wrote in message news:46d3e857.1434062(a)news.inet.tele.dk > On 27 Aug 2007 14:50:38 GMT, Arno Wagner <me(a)privacy.net> wrote: > > > Come to think of it, it may be that Linux typically reads (and > > writes?) 1kB or 2kB aligned on an address divisible by 2 or 4 > > respectively. Maybe only on SCSI, maybe on USB storage, maybe > > generally. On a fast browse through the sources of 2.6.18.8 I did not > > find anything relevant. > > > > This may mean that testing the presence of the problem under Linux > > could need a single-secor write (if Linux does that). If Linux > > allways does at least 1kB accesses aligned on an even address, then > > the problem would not manifest itself. If it only does this on > > reading, the problem could well be present for a single-sector write. > > > > Can you overwrite the critical sector with dd and then see > > whether it changed? > > > > Arno > > Reply no. 2. > > A variant of the problem can be seen in Linux. > > I made a partition on the USB Seagate disk beginning at sector 268435455: > > Disk: 4 Cylinders: 19457 Heads: 255 Sectors: 63 MB: 152625 > > --PCyl N ID -----Rel -----Num ---MB --Start CHS- ---End CHS-- BS CHS > 0 1 61 268435455 44141250 21553 16709# 85 16 19456*254 63 OK > > Then in Linux I did: > > dd if=/dev/sda of=sda.bin bs=512 count=1 skip=268435455 > > and > > dd if=/dev/sda1 of=sda1.bin bs=512 count=1 > > The file sda.bin has the correct content, while > sda1.bin has wrong content, and is different between different attempts. > This indicates that the sector was actually not read, without any warnings. Well, /something/ was read which explains the "without any warnings". |