Re: Filesystem Corruption (ext2) on Tyan S2462, 2xAMD1900MP, 2.4.17SMP (RH7.2)

[Alan Cox]

> We're seeing this with Tyan 2410s and Seagate drives.  I think Tyan just
> can't get DMA right.  Luckily we mainly lost docs or man pages before we
> disabled DMA, although losing the rpm database sucked.  MDMA2 seems okay
> but we haven't tested it long enough to form a lasting impression.
> I'm actually patching the ServerWorks driver to honor the CONFIG flag,
> since even with hdparm there is a narrow risk to the fs during the boot
> process before DMA is disabled.

I can confirm problems with serverworks OSB4 and UDMA. With UDMA and
a seagate disk you see 4 bytes repeat from one transfer into the next
shuffling all the data up 4 bytes (which since it includes inode and
metadata is *messy*). Current 2.4 has detect code that sometimes traps this
and panics to avoid fs death.

With MWDMA all was fine.

This was observed across a large number of boxes in a rendering farm so its
not a one off flawed box, and across two board vendors. I reported it to
serverworks who were interested but couldnt reproduce it in their lab.