is multipath -F safe? (flush all unused paths)

Question

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 ql-scan-lun.sh -r, which is supposed to do the same thing, can interrupt visibility of all the LUNS. using qlogic qla2xxx hbas.

What OS are you using? It looks Linuxy, but guessing could be catastrophic. — sysadmin1138, Dec 27 '10 at 21:00
@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
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

Mark Wagner · Accepted Answer · 2010-12-28T01:58:36.823

4

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.

See http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/removing_devices.html

edited Dec 28 '10 at 01:58

answered Dec 28 '10 at 01:52

Mark Wagner

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Actually, which OS are you using? My answer assumed RHEL5. – Mark Wagner Dec 28 '10 at 02:00
great, thanks. CentOS 5.2, so essentially RHEL5. – carillonator Dec 28 '10 at 17:39

is multipath -F safe? (flush all unused paths)

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