Linux Storage system: looking for advices Post: 302385283

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Special Forums Hardware Filesystems, Disks and Memory Linux Storage system: looking for advices Post 302385283 by pludi on Thursday 7th of January 2010 04:56:45 PM

01-07-2010

Registered User

Quote:

Originally Posted by Loic Domaigne

[...]
As expected, only the files from the failed partition were missing after the restore operation.[...]

Which is, usually, something you do not want to happen. Personally, I'd rather have a system that's a bit slower if a disk goes bad, but keeps on working, than losing files and not being able to use the system until I've got a replacement disk. But that might just be me.

Quote:

Originally Posted by Loic Domaigne

[...]
However, I failed to restore the file system if /dev/vda6 gets damaged. I used an alternate superblock for fsck (one located on vdb2 or vdb3), but no avail.[...]

That might be because of the striping done by LVM. The volume manager doesn't fill up the first disk, then the second, and so on, but first fills the first stripe (by default 4 MB) on the first disk, the first stripe on the second disk, and so on. With that scheme it might very well be that all superblocks end up on the same disk.

pludi

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vxr5check

vxr5check(1M)															     vxr5check(1M)

NAME

       vxr5check - verify RAID-5 volume parity

SYNOPSIS

       /etc/vx/bin/vxr5check [-i | -v] [-g diskgroup] volume

DESCRIPTION

       The vxr5check utility compares the parity of each stripe of a RAID-5 volume specified by volume.  vxr5check reads the data for each stripe,
       generates the parity for this stripe, and compares this parity with the existing parity.

       vxr5check can be run against the entire RAID-5 volume, or incrementally on RAID-5 stripe boundaries, by specifying the -i option.

OPTIONS

       -g diskgroup
		 Specifies the Veritas Volume Manager (VxVM) disk group name for the RAID-5 volume name for verification.  If this option  is  not
		 specified, the default disk group is determined using the rules given in the vxdg(1M) manual page.

       -i	 Verifies the RAID-5 volume incrementally per stripes.	If a parity mismatch is found, that stripe location is displayed.

       -v	 Verbose output for the incremental vxr5check verification.  The verbose option outputs each stripe number that is being verified.

OUTPUT FORMAT

       In  verbose  mode and incremental mode, summary reports for each stripe of the RAID-5 volume are printed in output records.  If an error is
       returned for a stripe, then an error message and stripe number are displayed.  In non-verbose mode, if an error is returned, an error  mes-
       sage is displayed.

       If a parity mismatch error is determined on a stripe, vxr5check exits on that stripe and does not continue for the remaining stripes in the
       RAID-5 volume.

FILES

       /usr/lib/vxvm/bin/vxr5vrfy    The utility that vxr5check calls to perform RAID-5 parity verification operations for  the  specified  RAID-5
				     volume.

EXIT CODES

       The  vxr5check  utility exits with a non-zero status if the attempted operation fails.  A non-zero exit code is not a complete indicator of
       the problems encountered, but rather denotes the first condition that prevented further execution of the utility.

       See vxintro(1M) for a list of standard exit codes.

NOTES

       Do not run vxr5check on a volume that is in degraded mode.

SEE ALSO

       vxevac(1M), vxintro(1M), vxmend(1M), vxvol(1M)

VxVM 5.0.31.1							    24 Mar 2008 						     vxr5check(1M)