Jochen M. Kaiser wrote:
Dear all,
we're currently looking forward to restructure our hardware environment for
our datawarehousing product/suite/solution/whatever.
cool.
We're currently running the database side on various SF V440's attached via
dual FC to our SAN backend (EMC DMX3) with UFS. The storage system is
(obviously in a SAN) shared between many systems. Performance is mediocre
in terms of raw throughput at 70-150MB/sec. (lengthy, sequential reads due to
full table scan operations on the db side) and excellent is terms of I/O and
service times (averaging at 1,7ms according to sar).
From our applications perspective sequential read is the most important factor.
Read-to-Write ratio is almost 20:1.
Do you do updates? Or is this a (more typical) append-mostly data warehouse?
Anton mentions why this is important when trying to predict the appropriateness
of ZFS.
We now want to consolidate our database servers (Oracle, btw.) to a pair of
x4600 systems running Solaris 10 (which we've already tested in a benchmark
setup). The whole system was still I/O-bound, even though the backend (3510,
12x146GB, QFS, RAID10) delivered a sustained data rate of 250-300MB/sec.
I'd like to target a sequential read performance of 500++MB/sec while reading
from the db on multiple tablespaces. We're experiencing massive data volume
growth of about 100% per year and are therefore looking both for an expandable,
yet "cheap" solution. We'd like to use a DAS solution, because we had negative
experiences with SAN in the past in terms of tuning and throughput.
Getting such high, sustained data rates with typical SAN-style systems becomes
quite expensive. The media can deliver 50-150 MBytes/s sequentially, but you
run into bottlenecks in all of the busses, controllers, loops, memory, and
copies of the data between the media and Oracle.
Being a friend of simplicity I was thinking about using a pair (or more) of 3320
SCSI JBODs with multiple RAIDZ and/or RAID10 zfs disk pools on which we'd
place the database. If we need more space we'll simply connect yet another
JBOD. I'd calculate 1-2 PCIe U320 controllers (w/o raid) per jbod, starting
with a
minimum of 4 controllers per server.
Yes, this is a natural progression. KISS.
Regarding ZFS I'd be very interested to know, whether someone else is running
a similar setup and can provide me with some hints or point me at some caveats.
I'd be also very interested in the cpu usage of such a setup for the zfs raidz
pools. After searching this forum I found the rule of thumb that 200MB/sec
throughput roughly consume one 2GHz Opteron cpu, but am hoping that someone
can provide me with some in depth data. (Frankly I can hardly imagine that this
holds true for reads).
Personally, I'd avoid raid-z for this, I'm a mirroring fan. We do have a
model for small, random reads, but don't have a good model for large, sequential
reads. You might have to do some tests to see where the performance envelope
is for your hardware.
I'd be also be interested in you opinion on my targeted setup, so if you have
any comments - go ahead.
Any help is appreciated,
Jochen
P.S. Fallback scenarios would be Oracle with ASM or a (zfs/ufs) SAN setup.
The same bottlenecks still remain, though.
-- richard
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