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from multipath manpage:

-F     flush all unused multipath device maps

is this a safe operation? I have a bunch of old dead paths and would like to clear them out, but want to make sure it's absolutely safe to do. I've heard -r, which is supposed to do the same thing, can interrupt visibility of all the LUNS. using qlogic qla2xxx hbas.

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What OS are you using? It looks Linuxy, but guessing could be catastrophic. – sysadmin1138 Dec 27 '10 at 21:00
"I ... would like to clear them out" - Why? – Chris S Dec 27 '10 at 21:09
@Chris, we are doing maintenance on our san switches and need to be able to see any newly failed paths, so having no failed paths to start is helpful. – carillonator Dec 27 '10 at 21:58
@sysadmin1138, multipathd is built into the linux kernel. – carillonator Dec 27 '10 at 22:00
Multipath (MPIO is the spec) is built into a lot of things, it comes out of the box in Win2008, Solaris, FreeBSD, and even NetWare, but Linux wasn't stated in your question or tags. – sysadmin1138 Dec 27 '10 at 22:51
up vote 4 down vote accepted

Yes, it is safe. However, if any other subsystem is using them (lvm, mount) or you have queued I/Os the paths won't be flushed and you'll need to figure out why.

Edit: use -f device to be safe.


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Actually, which OS are you using? My answer assumed RHEL5. – Mark Wagner Dec 28 '10 at 2:00
great, thanks. CentOS 5.2, so essentially RHEL5. – carillonator Dec 28 '10 at 17:39

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