Poor disk performance however no sign of failure Post: 302587280

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Operating Systems Solaris Poor disk performance however no sign of failure Post 302587280 by rbatte1 on Wednesday 4th of January 2012 11:36:46 AM

01-04-2012

Moderator

Plenty to look for here, not that this is an easy answer:-

Using vmstat (see your man page for what your output shows you) is your server paging a lot? Consider the placement of the page volumes/files. If you have matching memory and potentially there is a process consuming lost of memory, have a look with something like ps el|sort -n +9 based on the AIX version of ps so you will need to carefully read your man page for that. Take care to check if you want the flags with or without the leading hyphen.
Is there a process you don't expect running disk sync all the time? We have users of SQL tools forgetting where they are an initiating /usr/bin/update by mistake and that cripples us sometimes.
Are the disks actually comparable?
Are you the only user of both servers or is something else skewing your results?
Have you recently replaced a disk and one server is still mirroring? Are the RAID controller status displays showing that you are fully operational?
Is anything else hitting your network card and causing the server to spend some time responding to that?

Sorry to be soooo vague, but it's one of the less fun things you have to do as the system manager (more than just an administrator) in tracing what's going on and looking for contention. It can prove a costly time investment.

I hope that this helps somewhere, but I'm sure there will be other suggestions to trawl through too.

Robin
Liverpool/Blackburn
UK

rbatte1

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LEARN ABOUT DEBIAN

syncer

SYNCER(4)						   BSD Kernel Interfaces Manual 						 SYNCER(4)

NAME

     syncer -- file system synchronizer kernel process

SYNOPSIS

     syncer

DESCRIPTION

     The syncer kernel process helps protect the integrity of disk volumes by flushing volatile cached file system data to disk.

     The kernel places all vnode(9)'s in a number of queues.  The syncer process works through the queues in a round-robin fashion, usually pro-
     cessing one queue per second.  For each vnode(9) on that queue, the syncer process forces a write out to disk of its dirty buffers.

     The usual delay between the time buffers are dirtied and the time they are synced is controlled by the following sysctl(8) tunable variables:

     Variable	      Default	   Description
     kern.filedelay   30	   time to delay syncing files
     kern.dirdelay    29	   time to delay syncing directories
     kern.metadelay   28	   time to delay syncing metadata

SEE ALSO

     sync(2), fsck(8), sync(8), sysctl(8)

HISTORY

     The syncer process is a descendant of the 'update' command, which appeared in Version 6 AT&T UNIX, and was usually started by /etc/rc when
     the system went multi-user.  A kernel initiated 'update' process first appeared in FreeBSD 2.0.

BUGS

     It is possible on some systems that a sync(2) occurring simultaneously with a crash may cause file system damage.	See fsck(8).

BSD
								   July 14, 2000							       BSD