Re: About RA_PAGES
From: Informatica <navidul@retemail.es>
>
>I've a DSS style Server, I have this parameters in my ONCONFIG file:
>
># Read Ahead Variables
>
>RA_PAGES 1000 # Number of pages to attempt to read>ahead
>RA_THRESHOLD 500 # Number of pages left before next group>
>
>
>My AIO's working to much. Output of "onstat -g iov" :
>
>AIO I/O vps:
>class/vp s io/s totalops dskread dskwrite dskcopy wakeups io/wup
>errors
> msc 0 i 0.0 936 0 0 0 843
>1.1 0
> aio 0 s 9.4 743188 682740 60408 0 260139
>2.9 0
> aio 1 s 8.8 694198 642324 51860 0 214580
>3.2 0
> aio 2 s 8.4 669338 620532 48805 0 193024
>3.5 0
> aio 3 s 8.3 655764 612561 43202 0 181597
>3.6 0
> aio 4 s 8.1 643922 603802 40119 0 171931
>3.7 0
> aio 5 s 8.0 633544 598318 35225 0 163036
>3.9 0
> aio 6 s 7.8 621254 588774 32479 0 152565
>4.1 0
> aio 7 s 7.7 609731 580301 29429 0 142759
>4.3 0
> aio 8 s 7.5 597762 571123 26638 0 133127
>4.5 0
> aio 9 s 7.4 584992 560647 24344 0 123137
>4.8 0
> aio 10 s 7.2 571072 549016 22054 0 113977
>5.0 0
> aio 11 s 7.1 559445 539354 20089 0 105207
>5.3 0
> aio 12 s 6.9 548570 529858 18711 0 96963
>5.7 0
> aio 13 s 6.8 538166 520690 17475 0 89020
>6.0 0
> aio 14 s 6.7 530005 513450 16555 0 83058
>6.4 0
> aio 15 i 6.6 526492 510207 16285 0 78123
>6.7 0
> pio 0 i 0.0 2892 0 2892 0 2893
>1.0 0
> lio 0 i 0.1 10362 0 10362 0 10363
>1.0 0
>
>
>My system is:
>
>IDS 7.31.UC2 on HPUX-11.00. (HP-9000/L1000 One CPU 440Mhz)
>
>Load average of system when the motor is running is 16 (note: aio's =
>16)
>
>Well, after of this situation, I've decided to change number of aio's.
>
>onmode -p +20 aio>
>Well, After some time, I've observed:
>
>The value io/s down to 2 to 4. and the load of system grown to 36. (note
>aio's = 36)
>
>Well. What of the two situations is better ?.
>
>1.- The overhead in the system with a lot of aio's running. or
>2.- The overhead in the Server with few aios.
3. Seriously reduce RA_PAGES and RA_THRESHOLD. Try 32 and 28 or 16 and 12.
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