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From: keith@imagen.UUCP (Keith Rich)
Newsgroups: comp.sys.apollo
Subject: Mixed SR10.2/SR9.7 file system performance
Message-ID: <9400@imagen.UUCP>
Date: 15 Feb 90 18:53:08 GMT
Reply-To: keith@imagen.COM (Keith Rich)
Organization: Imagen Corporation, Santa Clara, CA
Lines: 46


We recently upgraded our file servers and we are getting slower
performance than we had expected.  I'd like advice from anyone who
has already been through this, or who can suggest what I might try
to tune.

We replaced six DSP80A/DSP90s with 500 MB disks, with one DN4000
with four 697 MB disks.  Most of our workstations are DN3010s with
4 MB of memory and the DSP80As had 3 MB of memory.  These systems
run SR9.7 for two reasons.  We have yet to convert some important
programs to run correctly on SR10.2 and we know we will need more
than 4 MB of memory to run SR10.2 efficiently.

The DN4000 has 12 MB of memory and is running SR10.2 because SR9.7
will only suport two disks.  The file system performs well directly
on the DN4000, but poorly when serving files for the SR9.7 DN3010s.
The degradation is perhaps a factor of 2.5, so I can't just forget
it.  I suspect that the bottleneck is some sort of interface between
SR9.7 and SR10.2, but I'm not sure what or why.  The performance
acts this way even when I'm only using a single disk, so it isn't
simply too many disks on one server.  If the ring net were the
bottleneck, then I not sure why the DSPs seem better than the
DN4000.

We are considering the following annoying choice.  Upgrade another
DN3010 to a DN4000, put two of the 697 MB disks on it, and downgrade
both DN4000s to SR9.7.  I'm reluctant to do this because it seems
to mean that I cannot migrate to SR10.2.  Instead, I will have to
cut everything over at once (if ever).  So, I fear that taking this
step will simply lock me into SR9.7 forever.

What other (better?) choices have I missed?  Where should I look
to find out more about how to tune things up?

I also had to deal with another annoying problem when I moved my
files from my SR9.7 disks to my SR10.2 disks.  I discovered that
using "cpt from to -pdt -sacl" preserved the Aegis ACLs, but lost
the Unix permissions.  Using "find ... | cpio -p ..." preserved
the Unix permissions, but lost the Aegis ACLs.  So I used cpt and
then wrote a program to recover the Unix permissions.  It worked
like "cd oldtree; find . -print | modtree oldtree newtree".  Has
anyone found a simpler, more direct way to do this?

Thanks (in advance),

Keith Rich (keith@imagen.com)