topic Forcing /dev/mpath/mpath* aliases in Operating System - Linux

Forcing /dev/mpath/mpath* aliases

Anthony Dyson — Thu, 28 Feb 2008 05:10:59 GMT

We used to have 16 LUN's where the numeric component of the /dev/mp-* -> /dev/mpath/mpath* symlinks all matched & were persistent over reboots. After adding 8 new LUNS, the symlinks have been reordered. For example, /dev/dm-0 is now symlinked to /dev/mpath/mpath8.

Does anyone know how to force the links back to the way they were before? The intention would be to make the new LUN's /dev/mp-16 >> 23 with corresponding /dev/mpath/mpath16 >> 23 symlinks.

Re: Forcing /dev/mpath/mpath* aliases

skt_skt — Fri, 29 Feb 2008 02:36:33 GMT

which linux version? could u post "/etc/modprobe.conf" and "rpm -qa|grep -i mapper"?

Do you use power path here?which HBA cards are used?

what real impact do you have due to the said change?

Re: Forcing /dev/mpath/mpath* aliases

Randy Jones_3 — Fri, 29 Feb 2008 04:08:17 GMT

Bindings of mpath IDs to volumes are retained in /var/lib/multipath/bindings (on my RHEL systems anyway) and new bindings to previously unknown volumes are assigned new entries at the bottom of the file. The lower-numbered path IDs you're looking for are bound to obsolete volumes.

Delete the file and let multipath recreate it, or edit it.

Re: Forcing /dev/mpath/mpath* aliases

Anthony Dyson — Fri, 29 Feb 2008 05:20:21 GMT

Randy Jones: thanks for that info. I'd become fairly sure that the mpath -> WWID relationships in the bindings file were really the important consideration, & that the "/dev/dm-*" devices are intentionally mutable & we shouldn't care. Now I won't try to mount a /dev/dm-* device again.

Re: Forcing /dev/mpath/mpath* aliases

skt_skt — Fri, 29 Feb 2008 18:23:09 GMT

dont you use VG(LVM) ?Just wondering why to mount using a dm device file.