topic Re: SCSI read write errors - disk failed in Operating System - HP-UX

SCSI read write errors - disk failed

Jonathan Caplette_1 — Mon, 16 Aug 2004 13:06:37 GMT

Hi there!

Since a few days, I've seen in my syslog errors related to SCSI... I'm running HP-UX 11i, I've check with ioscan the disk, fc, tape, ioscan alone with no classes, everything is CLAIMED. So I tried to fcmsutil the fiber cards they are ONLINE and I pvdisplay and diskinfo the disks related in my error (attached as my syslog error... dev_t=0x1fxxxxxx) all the disks listed as POWERFAILED respond to my pvdisplay and diskinfo!! What could I expect to give me that error???

Thanks
Jonathan

Re: SCSI read write errors - disk failed

Sundar_7 — Mon, 16 Aug 2004 13:19:40 GMT

Jonathan,

I believe PV timeout is the issue here. are your disks on a storage enclosure (EMC?) ?.

I get this errno=126 all time :-).

By default PV timeout is set to 30 secs. LVM queues the IO for the disk and if the disk did nt process the IO request within 30 secs, it assumes the LUN has gone bad and logs read/write errors.

PV TIME OUT is also the reason for those POWERFAILED error messages.

you can use pvchange command to set the PVTIMEOUT to a higher value.

man pvchange and look for -t option.

-- Sundar.

Re: SCSI read write errors - disk failed

Jonathan Caplette_1 — Mon, 16 Aug 2004 13:28:00 GMT

Sundar, and everyones,

I forgot, those disks are on a SAN.

I'm gonna check for the timeout option... Any other ideas???

Jonathan

Re: SCSI read write errors - disk failed

Jeff Schussele — Mon, 16 Aug 2004 13:29:05 GMT

Hi Jonathan,

As well as pvchange -t to change timeout on the PV level, you can use lvchange -t to change it at the LV level.
Default is 30 seconds - bump it to 60 to give you headroom under *heavy* disk I/O loads.

Rgds,
Jeff

Re: SCSI read write errors - disk failed

Sundar_7 — Mon, 16 Aug 2004 13:38:07 GMT

any other ideas ?? -- hmm, try out the timeout settings - I am positive it will solve the problem.

Re: SCSI read write errors - disk failed

Jonathan Caplette_1 — Mon, 16 Aug 2004 13:59:25 GMT

Is this error can cause performance issues??? And setting the timeout to 60 sec, will it affect the performance of the disks access???

Re: SCSI read write errors - disk failed

Sundar_7 — Mon, 16 Aug 2004 14:04:35 GMT

Nope, it is not going to cause performance problems.

Reducing the timeout value from 30 secs to 10 secs doesnt mean you will get the IO done faster :-).

It just defines the timeout for LVM after which it can conclude the IO to the LUN has failed.

Re: SCSI read write errors - disk failed

Jonathan Caplette_1 — Mon, 16 Aug 2004 14:55:41 GMT

Thanks for the advise!! I'll check the timeout on pv and lv's!!

Ciao!

Re: SCSI read write errors - disk failed

Jonathan Caplette_1 — Tue, 17 Aug 2004 11:42:25 GMT

I just got another question!! My disks that gave me that error, is on an HDS (Hitachi Data System) SAN, do I have some specific timeout option to set on my PV??? Or these options are generic??

Re: SCSI read write errors - disk failed

Sundar_7 — Tue, 17 Aug 2004 12:01:44 GMT

The timeout value is generic though the optimal timeout value is dependent on the hardware configuration of the SAN box (like the amount of cache it has, the amount of IO traffic and the number of channel adapters etc).

But here all you can do is to hit-and-trail.

Set the timeout to 60 and observe. If you are still seeing the read errors or POWERFAILED messages for the PV then you need to increase the PV timeout.

At 60, if there are no errors, you could experiment by lowering the timeout value.