PBUF/PSBUF/FSBUF question

[Miguel Sanders]

Hello gurus

After reading the man page on vmstat, it still isn't quite clear to me
what the pbuf/psbuf/fsbuf buffers mean in the following vmstat -v
output:
0 pending disk I/Os blocked with no pbuf
371595 paging space I/Os blocked with no psbuf
2178290 filesystem I/Os blocked with no fsbuf

The man page states
pending disk I/Os blocked with no pbuf
Number of pending disk I/O requests blocked because no pbuf was
available. Pbufs are pinned memory buffers used to hold I/O requests
at the logical volume manager layer.
paging space I/Os blocked with no psbuf
Number of paging space I/O requests blocked because no psbuf was
available. Psbufs are pinned memory buffers used to hold I/O
requests at the virtual memory manager layer.
filesystem I/Os blocked with no fsbuf
Number of filesystem I/O requests blocked because no fsbuf was
available. Fsbuf are pinned memory buffers used to hold I/O requests
in the filesystem layer.

Could someone give me an example when these counters get incremented?

Thanks a lot

[KS]

You might want to run vmstat over a period of time and monitor these
parameters, as due to shortfall of these buffers, I/O are blocked. You
can modify their settings thru "ioo". Here is the explanations as I
understand it:

pbuf: Are buffers defined and used at LVM level. (Use lvmo instead of
ioo).
psbuf: Are buffers are for paging space operation
fsbuf: Are for filesystems ("ioo"/"j2_nBufferPerPagerDevice")

-Khatir