Hi, this is a little late and not particularly XFS-specific but ...
> The machine is a Dual 500 MHz PIII, and the filesystems run on top of
> the 3ware IDE raid card with 4 46G disks running in RAID level 5.
> (138G filesystem available...) The XFS is the 2.4.3 version from
> April 5th.
3Ware sent me an e-mail about a problem they found with their Escalade
6400 controllers, RAID 5, and ext2. Their e-mail did not have conclusive
information on any other filesystem, but I'm thinking that XFS could be
affected, too. I "dirty hack" seems to be to mount the ext2 partition with
the sync option. Maybe XFS treats a disk in a similar manner, making XFS
"immune"?
Anywa, until a patch comes out (expected somewhere around May 15) for
their software, RAID 5 looks iffy. Or does it?
Here is a copy of the e-mail I got for whatever it's worth. :)
--> Jijo
---------- Forwarded message ----------
Date: Wed, 2 May 2001 09:24:15 -0700
From: Mike Wentz <mike.wentz@xxxxxxxxx>
Subject: 3ware Technical Bulletin concerning RAID 5
Important Technical Bulletin
Dear customer,
You are receiving this email because you are a registered
owner of a 3ware Escalade 6400 Series Storage
Switch, or you have opened a Tech Support case with 3ware
on a 6400, 6410 or 6800 Series Escalade Storage Switch.
3ware has found a bug in our RAID 5 code that can cause file
system errors resulting in possible loss of data. This
problem has only been experienced on Linux operating systems
running the default ext2 file system, however, other file
systems may be affected.
Products affected: Escalade 6400, 6410 and 6800
Software Versions affected: 6.5 and 6.6
RAID level affected: RAID 5
Operating systems affected:
Known: Linux with default ext2 file
system
Possible: Win98/ME, WinNT, Win2000
************************************************************
Symptoms:
1. 3ware BIOS VERIFY command reports VERIFY Failed.
2. Linux fsck -vf command returns inode and/or superblock
errors when run while the array is in degraded mode.
3. Windows chkdsk command returns errors on the MFT
(Master File Table).
************************************************************
Problem description:
1. In Linux, the RAID 5 parity data can get corrupted during
writes.
2. On Microsoft operating systems, parity and/or user data
can get corrupted during writes.
************************************************************
Is my data corrupted?
There are two factors that determine whether or not your
data is affected:
1. Whether or not the array has ever degraded
2. Which operating system you are using
If the array has never degraded, then the data should be
fine.
If the array has degraded, then there is a potential that
your data is affected. In most cases, the operating system
will detect the errors and correct them. It is possible,
however, that the operating system cannot detect and correct
all the errors, in which case you will need to restore from
backup.
To date, this problem has only been seen on Linux operating
systems running the ext2 default file system.
3ware has not yet found an instance where user data on a
Microsoft operating system has been affected, however, it is
theoretically possible.
************************************************************
I'm using RAID 5, what should I do?
Depending on your operating system and the state of the
array, the following actions are recommended:
Linux:
If the RAID 5 has never degraded there are two choices:
1. Reconfigure the array to RAID 1 or RAID 10.
2. Mount the file system in synchronous mode. Synchronous
mode will prevent the parity data from being affected,
thereby eliminating the problem. Please note that there
is a significant performance penalty.
Command syntax:
mount -t ext2 /dev/device_node /mountpoint -o sync
If the array has degraded run fsck to repair damaged data.
1. If the repair completes successfully, you may either
convert the array to RAID 1 or RAID 10, or run the file
system in synchronous mode.
2. If the repair is unsuccessful, you will need to restore
from backup.
Microsoft NT, 98, ME or 2000:
If the RAID 5 array has never degraded you should
reconfigure the array to RAID 1 or RAID 10.
If the array has degraded, run chkdsk /R to repair damaged
data.
1. If the repair completes successfully, reconfigure the
array to RAID 1 or RAID 10.
2. If the repair is unsuccessful, you will need to restore
from backup.
************************************************************
What happens if I stay on RAID 5?
1. 3ware does not recommend using RAID 5 on any Microsoft
operating system at this time.
2. If you are running Linux and wish to remain on RAID 5,
3ware recommends you mount the file system in synchronous
mode.
************************************************************
When will a RAID 5 fix be available?
1. 3ware has identified the cause of the problem and
developed a fix. We are in the process of testing to
insure that it completely corrects the problem. We
anticipate having the fix available on or before
May 15, 2001.
2. If you would like to register to be notified when the
fix is available please click here:
http://www.3ware.com/support/contact3wareraid5.asp
3ware regrets any inconvenience this problem may cause you.
Sincerely
Michael L. Wentz
Director, Customer Service (650.269.2977)
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