"external pager filesystem I/Os blocked with no fsbuf" refers to the
number of external pager client filesystem I/O requests blocked
because no fsbuf was available. JFS2 is an external pager client
filesystem. If this grows as in your case you can typically set
j2_nBufferPerPagerDevice to 1024 using ioo and check. The default
value is 512. The filesystem should be remounted for changed to take
effect.

Futher, I have also read in the help pages that ideally
j2_dynamicBufferPreallocation should be tuned first and this value can
be increased and if still you find the value of "external pager
filesystem I/Os blocked with no fsbuf" increasing, tune
j2_nBufferPerPagerDevice. This is because initially buffers are
alocated as per j2_nBufferPerPagerDevice and buffers are allocated and
destroyed dynamic past this value.

Also check for other buffer sizes too like pv_min_pbufs, munfsbufs
etc.
HTH
-Ashok

ad...@yahoo.com wrote:
> Original problem: Can not fork ... not enough resources - and box
> face plants
>
> Looking through nmon stats from before the crash the virtual memory
> sloooowly is used up till above happens.
>
> I've poured through all the stats and the "trend" I am fixated on
> now ...
>
> 12/20/07-21:27:06==== 429904 pinned pages
> 12/20/07-21:27:06==== 749500 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/20/07-22:27:06==== 431187 pinned pages
> 12/20/07-22:27:06==== 749514 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/20/07-23:27:06==== 431768 pinned pages
> 12/20/07-23:27:06==== 749545 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/21/07-00:27:06==== 432210 pinned pages
> 12/21/07-00:27:06==== 749574 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/21/07-01:27:06==== 433832 pinned pages
> 12/21/07-01:27:06==== 749626 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/21/07-02:27:06==== 434108 pinned pages
> 12/21/07-02:27:06==== 749687 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/21/07-03:27:06==== 434649 pinned pages
> 12/21/07-03:27:06==== 857633 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/21/07-04:27:06==== 435089 pinned pages
> 12/21/07-04:27:06==== 857678 external pager filesystem I/
> Os blocked with no fsbuf
>
> 12/21/07-05:27:06==== 435615 pinned pages
> 12/21/07-05:27:06==== 857717 external pager filesystem I/
> Os blocked with no fsbuf
>
> There iare no other obvious "problems" .. but I can see the virtual
> memory disappearing again ... and I'm 99% sure we will face plant
> eventually again.
>
> The increase in pinned pages seems to be related to a huge humongous
> tar that happens early morning. Everyday that happens the pinned pages
> jump a smidgen ... never to come down again ... but I can find no more
> info ... let alone how to fix it ...
>
> There are some tuning things I could potentially do - but I'm not just
> randomly going to change things hoping it does something ... I want to
> learn something ... ie KNOW what fixed it ....