A fix is available
APAR status
Closed as program error.
Error description
The?application?is?reading?64KB?from?a?file?in?a?filesyst em?occupying?a? striped?LV.?????????????????????????????????????????????? ?????????????? The?striped?LV?has?a?stripe?width?of?4?disks?(hdisk1,?hdi sk2,?hdisk3,??? hdisk4)?and?a?stripe?size?of?4KB.???????????????????????? ??????????????? The?trcrpt?report?shows?that?the?64KB?read?is?generating? a?read-ahead??? sequence,?with?the?first?read-ahead?being?page-ins?for?th e?first?8?????? pages.??????????????????????????????????????????????????? ??????????????? trcrpt?reports?that?this?is?processed?a?8?pstarts,?each?f or?4KB?each.??? ?Each?stripe?has?one?pstart?for?each?disk.?There?are?two? stripes?read,?? Thus?there?are?two?pstarts,?total,?for?each?disk.???????? ??????????????? ????????????????????????????????????????????????????????? ??????????????? The?detailed?problem?description?is?as?follows(?just?look ing?at?the????? first?transaction?(index?=?0.00):???????????????????????? ??????????????? In?the?filemon?collated?transaction?report,?all?of?the?LV M?pend?lines??? report?32?KB?for?the?bcount,?which?is?the?size?of?the?ent ire?read-ahead. They?should?be?reporting?4KB?each.??????????????????????? ??????????????? The?collated?report?also?provide?a?SCSIDD?iodone?line?wit h?its?own?????? bcount?value.???????????????????????????????????????????? ??????????????? There?is?one?of?these?for?each?disk,?each?reporting?8KB?w hich?is?correct for?the?total?data?sent?to?each?disk?(4KB?for?each?of?the ?two?stripes).
Local fix
Problem summary
The application is reading 64KB from a file in a filesystem occupying a striped LV. The striped LV has a stripe width of 4 disks (hdisk1, hdisk2, hdisk3, hdisk4) and a stripe size of 4KB. The trcrpt report shows that the 64KB read is generating a read-ahead sequence, with the first read-ahead being page-ins for the first 8 pages. trcrpt reports that this is processed a 8 pstarts, each for 4KB each. Each stripe has one pstart for each disk. There are two stripes read, Thus there are two pstarts, total, for each disk. In the filemon collated transaction report, all of the LVM pend lines report 32 KB for the bcount, which is the size of the entire read-ahead. They should be reporting 4KB each. The collated report also provide a SCSIDD iodone line with its own bcount value. There is one of these for each disk, each reporting 8KB which is correct for the total data sent to each disk (4KB for each of the two stripes).
Problem conclusion
Modified the code to print proper byte count for LVM pstart transactions.
Temporary fix
Comments
6100-07 - use AIX APAR IV58735 6100-08 - use AIX APAR IV58670 6100-09 - use AIX APAR IV58494 6100-09 - use AIX APAR IV58494 6100-09 - use AIX APAR IV58494 7100-01 - use AIX APAR IV56893 7100-02 - use AIX APAR IV58584 7100-03 - use AIX APAR IV58469 7100-04 - use AIX APAR IV58571
APAR Information
APAR number
IV58469
Reported component name
AIX V7.1
Reported component ID
5765H4000
Reported release
710
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Submitted date
2014-04-01
Closed date
2014-04-01
Last modified date
2016-05-10
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
AIX V7.1
Fixed component ID
5765H4000
Applicable component levels
R710 PSY U859719
UP14/05/22 I 1000
PTF to Fileset Mapping
U859719 bos.perf.tools 7.1.3.15
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Document Information
Modified date:
10 May 2016