At 10:52 AM -0500 1999/12/16, David Gilbert wrote:
> Now... using vinum and either the 2940U2W (Adaptec LVD) or the TekRAM
> (NCR) LVD (using the sym0 device) gives 30 to 35 M/s under RAID-5.
That's really interesting, because there are at least two or
three outstanding bugs in the vinum RAID-5 implementation that have
prevented me from successfully benchmarking it (see
<http://www.lemis.com/vinum/bugs.html>).
Have you been using rawio? Have you made any attempt to try
duplicating some of the sorts of benchmarks I've done, available at
<http://www.shub-internet.org/brad/FreeBSD/vinum.html>?
> This is impressive and subject to the bug that I mentioned in -STABLE
> which still hasn't been found.
Which one is this?
> The AMI MegaRAID 1400 delivers between 16.5 and 19 M/s (the 19M/s
> value is somewhat contrived --- using 8 bonnies in parrallel and then
> summing their results --- which is not 100% valid)... but the MegaRAID
> appears to be stable.
If you look at the page I mentioned, you'll see that my best
sustained speed with a vinum 4-way stripe on IBM 10kRPM 9LZX drives
attached to an Adaptec 2940UW controller was about 19MB/s sequential
read (anywhere from four to 128 processes), 16.5MB/s random read
(64-256 processes), 14MB/s sequential write (16 processes), and
15MB/s random write (64-256 processes).
My best performance with a DPT SmartRAID IV in a 4-way stripe
with the same disks was 16.5MB/s sequential read (4 processes),
7.5MB/s random read (pretty much regardless of how many processes),
17MB/s sequential write (256 processes), and 6MB/s (independent of
the number of processes). I did not attempt to benchmark DPT
SmartRAID IV performance under RAID-5.
I'd be very interested to see more extensive benchmarking of this
configuration. In addition to my page above, I'd recommend you look
at <http://www.acnc.com/benchmarks.html> and
<http://devlinux.com/projects/reiserfs/bens.html>, and see which of
these you can throw at your system.
With luck, in about a month or so, I should be getting a new
server in with 1GB RAM, 450Mhz Pentium III w/ 1MB L2 cache, a DPT
SmartRAID V controller with 256MB ECC cache, and eight Fujitsu
MAE3182LC 7200RPM 18GB drives for RAID-5 configuration on a single
SCSI bus, for our new anonymous ftp server.
I know this isn't an ideal configuration (I shouldn't have more
than four devices on a SCSI bus, and I should be using faster drives
with lower latency), but it will be very interesting to test out this
configuration with 3.4-RELEASE and what should hopefully be stable
DPT SmartRAID V/VI drivers by then. I plan on beating the crap out
of this machine before it goes online. ;-)
--
Brad Knowles <[EMAIL PROTECTED]> <http://www.shub-internet.org/brad/>
<http://wwwkeys.pgp.net:11371/pks/lookup?op=get&search=0xE38CCEF1>
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