heavy paging during large file copy? why?

[snippy]

Hello. I am running AIX 5.2 and I noticed today when I copy a pretty big file from one directory to another (on different file systems) my paging seemed to jump in a big way and the system is spending a lot of time in wait state (via topas). Anyone explain or seen this before?

# lsps -a
Pg Space - Phys Vol - Vol Group - Size - %Used
hd6 hdisk0 rootvg 3072MB 32

# vmstat 1 5
kthr memory page faults cpu
----- ----------- ------------------------ ------------ -----------
r b avm fre re pi po fr sr cy in sy cs us sy id wa
14 1 302579 358 0 5 6 30 131 0 276 4461 804 53 7 36 4
0 3 302583 190 0 152 0 0 0 0 408 2516 495 6 3 0 91
0 1 302583 163 0 147 0 130 524 0 389 2702 471 6 2 0 92
0 2 302585 131 0 152 0 130 290 0 415 2372 483 5 4 1 90
0 2 302585 158 0 153 0 195 325 0 456 2548 556 6 2 0 92
0 2 302585 175 0 156 0 195 443 0 432 2837 535 8 1 0 91

# vmstat -s
23935182 total address trans. faults
1504151 page ins
4209376 page outs
547251 paging space page ins
697659 paging space page outs
0 total reclaims
10331107 zero filled pages faults
25734 executable filled pages faults
14329224 pages examined by clock
59 revolutions of the clock hand
3300650 pages freed by the clock
389624 backtracks
0 lock misses
514147 free frame waits
0 extend XPT waits
681853 pending I/O waits
2276721 start I/Os
2276719 iodones
88046100 cpu context switches
30164236 device interrupts
0 software interrupts
0 traps
488410610 syscalls

 

[snippy]

One more thing, the file copy may have been a timing coincidence, I do have an Informix database running on this particualr box as well. Thats about it though.

 

[bi]

I had something similar (actually an ftp, which brings networking into the picture), but I don't know why it happened. The developers were ftp'ing a huge amount of data from an AS400 to our AIX system and the ftp kept failing. The errors I was getting in errpt (if I remember correctly) made me think it was because of lack of paging space (I had 2 GB of paging). So I upped it to 8 GB (1 GB for each GB of RAM) and the ftp was successful.

 

[raztaboule]

run svmon -G
"in use" under the column "work" gives you the amount of memory that you use for working segments and that will be page to paginspaces if necessary

run /usr/samples/kernel/vmtune
maxperm gives you the percentage of real memory where file pages won't be page before working segments.

so if you want to minimize the use of paging space use /usr/samples/kernel/vmtune -P <x> ( where X is the percentage of memory for file pages )get X lower than the value of maxperm.

do it carefully...
if you don't have paging in normal use , don't do it.

 

[MoshiachNow]

HI,

1.are both FS local or NFS mounted ?
2.A topas screen taken while the phenome is on could also help.

Thanks

&quot;Long live king Moshiach !&quot;

http://www.7for70.com/