pv timeout value

[nanan]

Hi there

I have a system using EMC storage system and
most the lvols fot DB data.

Could you please give me the best answer for PV time out value.
The reason i am asking is that i recieved a recommend i need to chnage the pv time out for all LUNs of EMC storage
Current value isn't

Give me the reasonable value and why

[A. Clay Stephenson]

The default value of 30 seconds makes sense for standalone disk drives and that is the basis of the decision of the default value. However, depending upon the disk array in use, timeouts of 120-180 seconds are more appropriate because the LUN's may go offline for that period of time especially while array configuration operations are being done. For example, when carving out a new LUN, all the disk devices associated with the array may appear unresponsive. Unless the timeout is set to a higher value, LVM will automatically try an alternate path.

[nanan]

Thanks your explanations
is it possible to change with pvchange -t XX /dev/dsk/cXtYdZ online ?
is there no impact the runing system ??

can you explain for the queue depth of SCSI
my system's is 32

How to estimate the reasonable value

[sathish kannan]

Hello Nanan,
yes PV timeout can be changed online with out any impact.

As Clay pointed out timeout value need to be set as per Storage vendor specifications. EMC usually recommends to use 180 secs for the above reason said.

Regards
Sathish

[nanan]

Thanks guys!!