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Full Discussion: iostat output vs TPC output (array layer)
Special Forums Hardware Filesystems, Disks and Memory iostat output vs TPC output (array layer) Post 302517231 by arizah on Tuesday 26th of April 2011 08:35:38 AM
Old 04-26-2011
iostat output vs TPC output (array layer)
Hi Guys,

I've been having some arguments with my colleagues about one thing. Always my thought was that as as far as disk performance is concern by looking at the output of the iostat command (AIX) you would be able to identify if you have a hot disk and then by moving some files out that disk or by making sure that the same disk is not share at the array level by another busy application would be good enough and I think it had worked for me for quite a few years. I think according to IBM and I'm saying IBM because we use IBM storage if a disk shows more that 35% time active then it could be be a sign of a performance degradation. Then assuming that I can shift around some files then I might be able to spread the I/O across multiple disks. If so do I still need to go the array level (raid) and check the performance stats (in out case TPC) or the output of the iostat would be more than enough. Basically I would like to know if the output of the iostat is accurate enough to determine if we are suffering a I/O bottleneck or if I still need to check the statistics/performance reports at the array raid level to be sure. Thanks in advance for your comments..
 

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LEARN ABOUT CENTOS

mkqdisk

mkqdisk(8)						      Quorum Disk Management							mkqdisk(8)

NAME

       mkqdisk - Cluster Quorum Disk Utility

WARNING

       Use of this command can cause the cluster to malfunction.

SYNOPSIS

       mkqdisk [-?|-h] | [-L] | [-f label] [-c device  -l label] [-d [-d ...]]

DESCRIPTION

       The mkqdisk command is used to create a new quorum disk or display existing quorum disks accessible from a given cluster node.

OPTIONS

       -c device -l label
	      Initialize  a new cluster quorum disk.  This will destroy all data on the given device.  If a cluster is currently using that device
	      as a quorum disk, the entire cluster will malfunction.  Do not run this on an active cluster  when  qdiskd  is  running.	 Only  one
	      device  on  the  SAN should ever have the given label; using multiple different devices is currently not supported (it is expected a
	      RAID array is used for quorum disk redundancy).  The label can be any textual string up to 127 characters - and is therefore  enough
	      space to hold a UUID created with uuidgen(1).

       -f label
	      Find the cluster quorum disk with the given label and display information about it.

       -L     Display information on all accessible cluster quorum disks.

       -d     Increase debugging level.  Specify multiple times for more information.  Currently, specifying more than twice has no effect.

SEE ALSO

       qdisk(5), qdiskd(8), uuidgen(1)

								     July 2006								mkqdisk(8)
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