I had questions on the validity of the recommendations the sys_check script
gives you, particularly for systems running oracle. I also questioned the
error:
> Operational: BMT pageCnt decreasing on AdvFS domain dat1_domain
> This should be checked IMMEDIATELY
because I didn't know how to look at M-6, which is what was recommended
in the section on what to do, and because it recommended running the
defragment cron job, and I had concerns about it being a hardware raid volume.
I received lots of good advice, as always, thanks to:
oisin_at_sbcm.com,M_Fliguer_at_miniphone.com.ar,tpb_at_doctor.zk3.dec.com,
asakelaris_at_cosmote.gr,joneskev_at_hotmail.com,brock_at_cs.unca.edu,
pgirish_at_binariang.maxisnet.com.my
I'll try to include the relevant info here. Essentially, M-6 is in the .tags
directory on advfs volumes, and there is no problem with raid hardware
striping,
just with advfs striping.
J. Reed - jreed_at_appliedtheory.com
==================================
The M-XX files (e.g, M-6, but others are possible) are
in the .tags directory at the top of each domain.
ex: cd /usr/.tags
showfile -x M-6
==================================
On the validity of sys_check recommendations, I would not say
to follow them blindly, of course, but in our case most of the time
they proved good (or harmless).
==================================
The fact that you have the whole AdvFS domain sitting on top of a RAID array
is irrelevant to the defragment utility. Unless you have created files that
are striped BY ADVFS ITSELF, then there's no problem (you can learn more on
AdvFS striping in the AdvFS documentation; trust me, it's usually a whole
lot more trouble to set it up than it's worth, hardware RAID or LSM works a
whole lot better).
==================================
Issue showfile -x .tags/M-6 on the domain in question.
Your extents should not exceed 200-300, and the pageCnt should be
linear. If you see holes like 128, 1, 5, 8 then you have a very fragmented
file system. Defrag immediatly, and on a nightly basis (crontab).
ls -l .tags/M-6 shows the size of the BitMapTable of your advfs.
==================================
M-6 is not the frag file. It is the BMT itself.
==================================
sys_check does know if there is oracle if the oracle is running at the time of
syscheck.
syscheck tuning recommandation you can take with pinch of salt as far as UBC
or vmxxxx parameters are concerned.
as you will have to independently check all such considerations. Or run
syscheck after your typical workload is done which gives little more accurate
information.
==================================
Received on Tue Nov 17 1998 - 16:29:54 NZDT