On Fri, 18 Jan 2008, Greg Cormier wrote:
Justin, thanks for the script. Here's my results. I ran it a few times
with different tests, hence the small number of results you see here,
I slowly trimmed out the obvious not-ideal sizes.
Nice, we all love benchmarks!! :)
System
---
Athlon64 3500
2GB RAM
4x500GB WD Raid editions, raid 5. SDE is the old 4-platter version
(5000YS), the others are the 3 platter version. Faster :-)
Ok.
/dev/sdb:
Timing buffered disk reads: 240 MB in 3.00 seconds = 79.91 MB/sec
/dev/sdc:
Timing buffered disk reads: 248 MB in 3.01 seconds = 82.36 MB/sec
/dev/sdd:
Timing buffered disk reads: 248 MB in 3.02 seconds = 82.22 MB/sec
/dev/sde: (older model, 4 platters instead of 3)
Timing buffered disk reads: 210 MB in 3.01 seconds = 69.87 MB/sec
/dev/md3:
Timing buffered disk reads: 628 MB in 3.00 seconds = 209.09 MB/sec
Testing
---
Test was : dd if=/dev/zero of=/r1/bigfile bs=1M count=10240; sync
64-chunka.txt:2:00.63
128-chunka.txt:2:00.20
256-chunka.txt:2:01.67
512-chunka.txt:2:19.90
1024-chunka.txt:2:59.32
For your configuration, a 64-256k chunk seems optimal for this, hypothetical
benchmark :)
Test was : Unraring multipart RAR's, 1.2 gigabytes. Source and dest
drive were the raid array.
64-chunkc.txt:1:04.20
128-chunkc.txt:0:49.37
256-chunkc.txt:0:48.88
512-chunkc.txt:0:41.20
1024-chunkc.txt:0:40.82
1 meg looks like its the best, which is what I use today, 1 MiB chunk offers
the best peformance by far, at least with all of my testing (with big files)
such as the tests you performed.
So, there's a toss up between 256 and 512.
Yeah for DD performance, not real-life.
If I'm interpreting
correctly here, raw throughput is better with 256, but 512 seems to
work better with real-world stuff?
Look above, 1 MiB got you the fastest unrar time.
I'll try to think up another test
or two perhaps, and removing 64 as one of the possible options to save
time (mke2fs takes a while on 1.5TB)
Also, don't use ext*, XFS can be up to 2-3x faster (in many of the
benchmarks).
Next step will be playing with read aheads and stripe cache sizes I
guess! I'm open to any comments/suggestions you guys have!
Greg
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