[dm-devel] dm howto?

gfbarros at ualr.edu gfbarros at ualr.edu
Sun Jun 13 03:15:01 UTC 2004


is there documentation somewhere on making dm work with multipath in rhel3? im just wondering if most of this is already in the kernel provided by redhat before i start tearing things apart and rebuilding :)

ive played with using mdadm a bit but it doesnt seems to deal with noticing dead paths and re-adding them too well...

Ive also noticed that disks presented by one of my controllers (hsv100) are not ready:

SCSI device sdb: 2097152 512-byte hdwr sectors (1074 MB)
sdb: asking for cache data failed
sdb: assuming drive cache: write through
 sdb:<6>Device sdb not ready.
end_request: I/O error, dev sdb, sector 0
Buffer I/O error on device sdb, logical block 0
Device sdb not ready.
end_request: I/O error, dev sdb, sector 0
Buffer I/O error on device sdb, logical block 0
 unable to read partition table

but i only see this in my Debian box, the RHEL3 one only actually sees one path per controller pair... which im guessing is the one to the active controller. Im guessing that bad things would happen if that controller died, as the kernel would need me to reload the qla2300 module before seeing the new presentation... im assuming report_lun fixes this, how do i set that in the stock kernel? or am i sol?

would this have something to do with the HSV's not being really active-active? how is this dealt with? (is this the group_by_tur feature in multipath-tools?)

if this is not the right list for these questions, please steer me in the right direction :) 

help is appreciated :)

thanks!
-guil




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