My tuppence worth, in the book Scaling Oracle Tuning, the author
poo-poo's the idea that modern storage arrays still need filesystem
segregation, saying that there is so much caching and buffering going on in
the array hardware, like EMC and Hitachi, that you will achieve very little
by segregating the drives out. When you segregate you only end up talking to
the array "interface" anyway and you have no real way of knowing exactly
which disks it has selected for which filesystems.
Sounds like one of those classic arguments, that usually only gets
solved through a compromises. If possible you could try contacting your
account managers from Oracle and the hardware manufacturers to ask if you
can talk to other customers and get their opinion, we do that here when it's
possible. You've already bought the stuff, so they are not going to lose you
as a customer!
-----Original Message-----
From: Stephen Lee [mailto:Stephen.Lee@xxxxxxxx]
Sent: 13 Dec 2004 18:30
To: oracle-l@xxxxxxxxxxxxx
Subject: Storage array advice anyone?
There is a little debate going on here about how best to setup a new system
which will consist of IBM pSeries and a Hitachi TagmaStore 9990 array of 144
146-gig drives (approx. 20 terabytes). One way is to go with what I am
interpreting is the "normal" way to operate where the drives are all
aggregated as a big storage farm -- all reads/writes go to all drives. The
other way is to manually allocate drives for specific file systems.
Some around here are inclined to believe the performance specs and
real-world experience of others that say the best way is keep your hands off
and let the storage hardware do its thing.
Others want to manually allocate drives for specific file systems. Although
they might be backing off (albeit reluctantly) on their claims that is it
required for performance reasons, they still insist that segregation is
required for fault tolerance. Those opposed to that claim insist that the
only way (practically speaking) to lose a file system is to lose the array
hardware itself in which case all is lost anyway no matter how the drives
were segregated, and if they really wanted fault tolerance they would have
bought more than one array. And around and around the arguments go.
Is there anyone on the list who would like to weigh in with some real world
experience and knowledge on the subject of using what I suppose is a rather
beefy, high-performance array.
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