PV Timeout value

 
CPHVF-U Guard
Advisor

PV Timeout value

Hi all

Is it possible to get the default pv timeout value from the sdisk driver. When using pvdisplay the output indicates that IO Timeout is set to default.....But no indication what the default value is?

Furthermore anybody knows if there is special need for pv timeout settings in an EMC SRDF metrocluster environment, other than the 90 seconds EMC recommends.
6 REPLIES 6
Victor BERRIDGE
Honored Contributor

Re: PV Timeout value

Hi,
I dont think you will find the value when you see "default", it is specific to the drivers...For sdisk driver (most commonly used), the default timeout is 30 seconds.
About your second question I dont know since I have no EMC but with HDS you can also tune the Queue Depth parameter...

All the best
Victor
Jeff Schussele
Honored Contributor

Re: PV Timeout value

Actually the default timeout is HW specific.
But it is logged by the driver into the kernel.
Varies from device to device.
I've seen as high as 180 for NetApp and as low as 30 for an EMC DMX.
And, no, take the EMC recommendation of 90 - they know better than anyone else.

My $0.02,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
CPHVF-U Guard
Advisor

Re: PV Timeout value

OK thanks.

But how did you find out that the default value is 30 seconds?
AshishJain_USA
Frequent Advisor

Re: PV Timeout value

Hi

I am not sure how to find out the default PV Timeout value.
As regards your 2nd Question, it all depends on what kind of I/Os are being generated on your SAN and whether you are getting frequent error messages in your syslog file related to PVs .

rgds..Ashish
Pat Obrien_1
Regular Advisor

Re: PV Timeout value

I too was a believer that the default sdisk driver timeout was 30 seconds. However I was recently corrected by the HP Mission critical response center that the actual value is 2 seconds, and that 5 retries will occur before a error is logged.
Mridul Shrivastava
Honored Contributor

Re: PV Timeout value

The PV timeout is limited by LVM_MIN_IO_TIMEOUT (2) and LVM_MAX_PV_IO_TIMEOUT (300).
PV I/O time out range can not be modified.
Time has a wonderful way of weeding out the trivial