LVM PV timeput vs LV timeout

[Ed Sampson]

Whats the relationship between pv timeout and lv timeout? If I set the PV timeout do I need to set the LV timeout, or are they the same thing?

[harry d brown jr]

Why would you want to modify the default behaviour of the pv and lv timeouts?

a pv is a physical volume (Usually a disk, or a pseudo disk - as on an emc or diskarray).

a lv is a slice of a pv, or sometimes the whole thing.


live free or die
harry

[Sanjay_6]

Hi Ed,

Take a look at the threads below,

http://us-support2.external.hp.com/cki/bin/doc.pl/sid=feff137f0c60163595/screen=ckiDisplayDocument?docId=200000024625751

http://us-support2.external.hp.com/cki/bin/doc.pl/sid=99cebb5001cd186263/screen=ckiDisplayDocument?docId=200000015663097

Hope this helps.

Regds

[Roger Baptiste · Accepted solution]

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By theory, yes. they are
different. LV timeout is
at the LV level and specifies how long a request to the LV should wait for response, before it times out. The default LV timeout value is "'Forever"" and I have *NEVER* seen it modified anywhere . Why? Because it does not matter. What matters is the PV timeout value. The pV timeout is at the PV layer and it specifies how long a request to the PV should wait before it times-out. PVtimeout overrides LV timeout, so LV timeout is largely irrelevant and should remain unchanged from its default value.

Regarding the timeout concept, it is to allow delays in response from the disks. For instance, while using EMC disks,we increase the PV timeout to 180 seconds. Otherwise, it may
consider a valid delay as disk unaccessible errors.

Bottomline: Timeout refers to PV timeout.

-raj

[Ed Sampson]

We are hooked to an EMC disk array. EMC is getting ready to do an online code upgrade to the EMC box, and ask us to check that the OS timeout value be set to 120. We already have are PV's set to 180 per earlier recommendations. Do we need to set the LV timeout? should it be the same or smaller than the PV timeout?

[Ed Sampson]

Thanks Raj, We will let LV timeout default.

[Sanjay_6]

Hi Ed,

Here are two links from hp doc site on lvchange and pvchange which details about the timeout variable.

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B9106-90008/B9106-90008_top.html&con=/hpux/onlinedocs/B9106-90008/00/02/207-con.html&toc=/hpux/onlinedocs/B9106-90008/00/02/207-toc.html&searchterms=timeout%7cdisk%7cvolume&queryid=20011107-075108

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/B2355-90681/B2355-90681_top.html&con=/hpux/onlinedocs/B2355-90681/00/02/270-con.html&toc=/hpux/onlinedocs/B2355-90681/00/02/270-toc.html&searchterms=pvchange&queryid=20011107-075537

Hope this helps.

Regds