SUMMARY: Solaris Volume Manager (SVM) Performance, Soft Partitions

SUMMARY: NFS Sharing: Directories vs. Filesystems

First, I'd like to thank the following list members for their time and
effort in replying, and their insight and advice:

Gregory Shaw
Kevin Buterbaugh
JV
David Foster
Anthony Talltree
Bevan Broun
Jeff van Eek
Darren Dunham
Tim Villa
Wes Garland
Sonny Baillargeon
Chad Johnson

As I suspected, these are/were questions to which there is no single (or
easy) answer.  There are advantages and disadvantages to all solutions,
and what works in one place may not work in another.  In other words,
"Your mileage may vary."

The general consensus is that SVM soft partition fragmentation is
potentially detrimental to I/O performance.  That degradation in
performance can be somewhat mitigated by a hardware RAID device since it
[presumably] will spread the load between spindles, minimizing
head-thrashing on a single disk.

As far as sharing directories vs. sharing filesystems is concerned, I
discovered that I was incorrect in assuming that sharing directories was
a result of poor design and/or implementation.  It seems it's a pretty
common occurrence, and there are some advantages to sharing at that
level.

My implementation:

We had a last-minute change in requirements that caused us to modify our
original plan.  I created a single 447GB sub-mirror using each cluster
RAID device (i.e. /dev/did/rdsk/d?s0) and mirrored it at that level.
>From there, I created two soft partitions; one is 300GB for our
NFS/Samba data, the second is 100GB for Clearcase VOBs.  The remaining
47GB is available for growth of the VOBs partition.

I had originally intended to make this a very comprehensive summary, but
I don't have enough time to devote to it, and I apologize for that.  I
do hope, however, that someone can make use of the information.

Gary Chambers

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// MIT Lincoln Laboratory / 781-981-0957
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// Nothing fancy and nothing Microsoft
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