File header cache size

[Wim Van den Wyngaert]

I'm doing some experiments.

Created 500 directories with 100 files each.

I put ACP_HDRCACHE on 55000.

Did a dir/siz=all of all files. Header hit rate 0% (fine).

Did a 2nd dir (same one). Also 0%.

I don't know the size of a file header but if it's 1 block or less than 2, why is then the hit rate 0 ?

Wim

[Volker Halle]

Wim,

does the 'Maximum buffers in FCP cache' value returned by 'SHOW DEV/FULL disk' reflect your new increased value of ACP_HDRCACHE ?

Does SDA> CLUE XQP/CACHE show an approriately big value in the Poolcnt line in buffer pool #2 (file header blocks are allocated from buffer pool #2) ?

If no, you may need to reboot (maybe after running AUTOGEN ?!). The XQP buffers are allocated from paged pool, which is allocated when the system disk is mounted.

You can look at the cached file header buffers with SDA> clue xqp/Buff=2

To look at the file header buffer itself, use SDA> clue xqp/bfrd= (index from column 1 of previous display). Then use the buffer address displayed and do SDA> EXA bufaddr;200 - this will shown you the file header in memory.

This is all 'interesting stuff' ;-)

Volker.

[Wim Van den Wyngaert]

Volker,

Maximum buffers in FCP cache is 24. So far from 55.000.

Poolcnt is only C.

Clue xqp returns 11 rows only.

It's an AS500 but I didn't use autogen to modify the parameter. If I do a sysgen show it's on 55.000.

???

WIm

[Volker Halle]

Wim,

enter MIN_ACP_HDRCACHE=55000 in MODPARAMS.DAT and run @AUTOGEN GETDATA GENPARAMS to see the effects on PAGEDYN. Then decide, if you want to activeate this parameter using @AUTOGEN GETDATA SETPARAMS and reboot.

Volker.

[Wim Van den Wyngaert]

Did that. Boot is just finished.

Pagedyn is now a lot higher (3.2M was 1.8).

All show/sda commands still hgave the same result.

No message was given during boot.

Wim

[Volker Halle]

Wim,

55000 file headers (ACP_HDRCACHE) would need about 28 MByte of paged pool. One file header = one disk block = 512 bytes.

?!

Volker.

[Ian Miller.]

If you compare old and new versions of SYS$SYSTEMS:PARAMS.DAT what changed?

[Wim Van den Wyngaert]

Small error. Pagedyn is on 32M not 3.2.

Diff :
SYSMWCNT 38121 was 4026
PAGEDYN 32M was 1.8
and some autogen antenna tuning.

Wim

[Volker Halle]

Wim,

now what about:

$ SHO DEV/FULL disk and Maximum buffers in FCP cache ?

SDA> CLUE MEM/STAT ! File System Cache params on 3rd page

$ SHO MEM/POOL should show Paged Dynamic Memory is use 28M or more.

Volker.

[Wim Van den Wyngaert]

Volker,

As said, all show commands result in the same value as before the autogen.

The new commands I will check tomorrow at 8 (German time=Belgian time).

Wim