Best Config KVM, Benchmark Disk Speed

Mon, 20 Jan 2014 05:33:37 GMT

Hi ,

Sir we recommend it to use default Caching if the server is production server .

default is the caching used by default by the kvm .

Writethrough caching means that the host
page cache will be used to read and write data but write notification will
be sent to the guest only when the data has been reported as written by the
storage subsystem.

Writeback caching will report data writes as completed as soon as
the data is present in the host page cache. This is safe as long as you trust your host.
If your host crashes or loses power, then the guest may experience data corruption.

The host page cache can be avoided entirely with cache='none'.
This will attempt to do disk IO directly to the guests memory.

Fri, 17 Jan 2014 22:02:19 GMT

Hi,

Code
$ for x in $(seq 1 10); do echo $x $(dd if=/dev/zero of=test_data.bin oflag=dsync conv=fdatasync bs=104857600 count=1 2>&1 | grep --only-matching -E "[0-9]+\.?[0-9]+ [kKmMgGtT]B/s"); done | tee test_data_write_times.txt

Results:
1 77.2 MB/s
2 78.4 MB/s
3 82.3 MB/s
4 74.2 MB/s
5 81.0 MB/s
6 109 MB/s
7 105 MB/s
8 83.6 MB/s
9 82.4 MB/s
10 93.6 MB/s

The test was done with disk settings:

The same test using the config:

Results:
1 13.3 MB/s
2 33.3 MB/s
3 29.1 MB/s
4 26.7 MB/s
5 35.0 MB/s
6 7.2 MB/s
7 22.5 MB/s
8 30.8 MB/s
9 37.2 MB/s
10 35.7 MB/s

Dear Virtualizor team which is the fastest and safest configuration to use in production?

L.S.N.