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Operating Systems AIX AIX System paramerter for Disk performance Post 302096752 by gogogo on Friday 17th of November 2006 08:11:34 PM
Old 11-17-2006
Is it the only direct way to fix the question?


File system buffer tuning
The following ioo and vmstat -v parameters can be useful in detecting I/O buffer bottlenecks and tuning disk I/O:

Counters of blocked I/Os due to a shortage of buffers
The vmstat -v command displays counters of blocked I/Os due to a shortage of buffers in various kernel components. Here is part of an example of the vmstat -v output:
...
0 paging space I/Os blocked with no psbuf
2740 filesystem I/Os blocked with no fsbuf
0 external pager filesystem I/Os blocked with no fsbuf

...
The paging space I/Os blocked with no psbuf and the filesystem I/Os blocked with no fsbuf counters are incriminated whenever a bufstruct is unavailable and the VMM puts a thread on the VMM wait list. The external pager filesystem I/Os blocked with no fsbuf counter is incriminated whenever a bufstruct on an Enhanced JFS file system is unavailable
The numfsbufs parameter
If there are many simultaneous or large I/Os to a filesystem or if there are large sequential I/Os to a file system, it is possible that the I/Os might bottleneck at the file system level while waiting for bufstructs. You can increase the number of bufstructs per file system, known as numfsbufs, with the ioo command. The value takes effect only when a file system is mounted; so if you change the value, you must then unmount and mount the file system again. The default value for numfsbufs is currently 93 bufstructs per file system.
 

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IOSTAT2PCP(1)						       Performance Co-Pilot						     IOSTAT2PCP(1)

NAME
iostat2pcp - Import iostat data and create a PCP archive SYNOPSIS
iostat2pcp [-v] [-S start] [-t interval] [-Z timezone] infile outfile DESCRIPTION
iostat2pcp reads a text file created with iostat(1) (infile) and translates this into a Performance Co-Pilot (PCP) archive with the basename outfile. If infile is "-" then iostat2pcp reads for standard input, allowing easy preprocessing of the iostat(1) output with sed(1) or similar. The resultant PCP archive may be used with all the PCP client tools to graph subsets of the data using pmchart(1), perform data reduction and reporting, filter with the PCP inference engine pmie(1), etc. A series of physical files will be created with the prefix outfile. These are outfile.0 (the performance data), outfile.meta (the metadata that describes the performance data) and outfile.index (a temporal index to improve efficiency of replay operations for the archive). If any of these files exists already, then iostat2pcp will not overwrite them and will exit with an error message. The first output sample from iostat(1) contains a statistical summary since boot time and is ignored by iostat2pcp, so the first real data set is the second one in the iostat(1) output. The best results are obtained when iostat(1) was run with its own -t flag, so each output sample is prefixed with a timestamp. Even better is -t with $S_TIME_FORMAT=ISO set in environment when iostat(1) is run, in which case the timestamp includes the timezone. Note that if $S_TIME_FORMAT=ISO is not used with the -t option then iostat(1) may produce a timestamp controlled by LC_TIME from the locale that is in a format iostat2pcp cannot parse. The formats for the timestamp that iostat2pcp accepts are illustrated by these examples: 2013-07-06T21:34:39+1000 (for the $S_TIME_FORMAT=ISO). 2013-07-06 21:34:39 (for some of the European formats, e.g. de_AT, de_BE, de_LU and en_DK.utf8). 06/07/13 21:34:39 (for all of the $LC_TIME settings for English locales outside North America, e.g. en_AU, en_GB, en_IE, en_NZ, en_SG and en_ZA, and all the Spanish locales, e.g. es_ES, es_MX and es_AR). In particular, note that some common North American $LC_TIME settings will not work with iostat2pcp (namely, en_US, POSIX and C) because they use the MM/DD format which may be incorrectly converted with the assumed DD/MM format. This is another reason to recommend setting $S_TIME_FORMAT=ISO. If there are no timestamps in the input stream, iostat2pcp will try and deduce the sample interval if basic Disk data (-d option for iostat(1)) is found. If this fails, then the -t option may be used to specify the sample interval in seconds. This option is ignored if timestamps are found in the input stream. The -S option may be used to specify as start time for the first real sample in infile, where start must have the format HH:MM:SS. This option is ignored if timestamps are found in the input stream. The -Z option may be used to specify a timezone. It must have the format +HHMM (for hours and minutes East of UTC) or -HHMM (for hours and minutes West of UTC). Note in particular that neither the zoneinfo (aka Olson) format, e.g. Europe/Paris, nor the Posix TZ format, e.g. EST+5 is allowed for the -Z option. This option is ignored if ISO timestamps are found in the input stream. If the timezone is not specified and cannot be deduced, it defaults to "UTC". Some additional diagnostic output is generated with the -v option. iostat2pcp is a Perl script that uses the PCP::LogImport Perl wrapper around the PCP libpcp_import library, and as such could be used as an example to develop new tools to import other types of performance data and create PCP archives. CAVEAT
iostat2pcp requires infile to have been created by the version of iostat(1) from <http://freshmeat.net/projects/sysstat>. iostat2pcp handles the -c (CPU), -d (Disk), -x (eXtended Disk) and -p (Partition) report formats (including their -k, -m, -z and ALL variants), but does not accommodate the -n (Network Filesystem) report format from iostat(1); this is a demand-driven limitation rather than a technical limitation. SEE ALSO
Date::Format(3pm), Date::Parse(3pm), iostat(1), LOGIMPORT(3), PCP::LogImport(3pm), pmchart(1), pmie(1), pmlogger(1) and sed(1). 3.8.10 Performance Co-Pilot IOSTAT2PCP(1)
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