On 12 Jul 2012, Brian Candler wrote:
> I don't believe he is getting that speed with cache=writethrough. I think
> he means cache=writeback.
No, I meant writethrough. Initially I had just done dd
using something like:
---
$ dd if=/dev/zero of=/home/user/testing bs=1024k count=1000
1000+0 records in
1000+0 records out
1048576000 bytes (1.0 GB) copied, 20.1434 s, 52.1 MB/s
This is on a guest with 512MB of RAM.
But then I added sync and made the file bigger for a
little bit more accuracy:
---
$ dd if=/dev/zero of=/home/user/testing bs=1024k count=2000 conv=sync
2000+0 records in
2000+0 records out
2097152000 bytes (2.1 GB) copied, 53.372 s, 39.3 MB/s
And finally I just tried fio using:
---
[global]
ioengine=sync
direct=1
rw=write
bs=128k
size=512m
directory=/home/user/data1
[file1]
iodepth=4
[file2]
iodepth=32
[file3]
iodepth=8
[file4]
iodepth=16
---
which gave:
---
WRITE: io=2048.0MB, aggrb=32217KB/s, minb=8054KB/s, maxb=8212KB/s, mint=63842msec, maxt=65093msec
That's probably a lot closer to accurate, 32MB/s give or
take. Sorry for the less than scientific approach initially. :)
--
Mark Nipper
nipsy at bitgnome.net (XMPP)
+1 979 575 3193
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