Timeout parameters in LVM

[G. Vrijhoeven]

Hi all,

I have a question about LVM. Is it possible to view/alter the timeout parameter for switching from the primairy path to the alternate path? and back?

In the man page I only found:

LVM automatically switches to the alternate link to access the physical volume.

On lvol level you can specify a I/O timeout parameter but that defaults to forever.

Thanks in advance.

Gideon

[Dietmar Konermann · Accepted solution]

Gideon,

there are two configurable LVM timeouts... the PV timeout (pvchange -t x) and the I/O timeout (lvchange -t). The PV timeout defauls to 30 seconds while the I/O timeout default to 'forever'.

The switching to the alternate path is guaranteed to happen within (2* pvtimeout +15) secs... however, with recent LVM patches it usually happens earlier, but never before pvtimeout secs.

You should NEVER touch the I/O timeout setting if the LV is used for a file system! This parameter is only for applications that directly access the raw LVs and know how to handle IO errors passed up to them.

Best regards...
Dietmar.

[G. Vrijhoeven]

Thanks Dietmar,

That was the info i was looking for.

Gideon