Linux – How to interpret IOZone results

hard drivelinuxlvmnetwork-attached-storageperformance

Here are the resuts of running IOZone on an ext3 filesystem on an LVM volume residing on a SAN LUN (it was ran with 5 parallel processes).

"Throughput report Y-axis is type of test X-axis is number of processes"
"Record size = 4 Kbytes "
"Output is in Kbytes/sec"

" Initial write " 81628.55

" Rewrite " 83354.72

" Read " 115595.02

" Re-read " 119306.09

" Reverse Read " 47684.20

" Stride read " 10011.09

" Random read " 16751.27

" Mixed workload " 5659.77

" Random write " 1661.85

" Pwrite " 36030.83

Now this is all nice and dandy, but my question is: how do I know whether the values are as good as they could be or there is something to tweak (and if so, what?)

The actual usage I will have for that Logical Volume is to act as virtual disk for a VM.

Best Answer

Ok, well you've not told us how many disks of what type on what SAN but I'm guessing this is a RAID 5 array of 4/5 x 7.2krpm disks via iSCSI over a 1Gbps NIC (?) - if that's the case then that seems fine really - it depends what you're using it for, again you don't mention.

If it's anything else then come back with more details of what you've got and what you want it for and I'll do what I can.

edit - is this an IBM N5000/6000? It feel like it might be.

Related Solutions

Linux Bash – How to Sort du -h Output by Size

As of GNU coreutils 7.5 released in August 2009, sort allows a -h parameter, which allows numeric suffixes of the kind produced by du -h:

du -hs * | sort -h

If you are using a sort that does not support -h, you can install GNU Coreutils. E.g. on an older Mac OS X:

brew install coreutils
du -hs * | gsort -h

From sort manual:

-h, --human-numeric-sort compare human readable numbers (e.g., 2K 1G)

Linux – How to interpret iozone values

It's strange that there doesn't seem to be a standard for IOPS measurement in Linux. These questions come up often when people are asked to provide an estimate of IOPS for capacity planning or storage sizing. I end up using multiple tools to gain this info. First, you'll need to generate a load using the method of your choice; either a representative application load, or something like the iozone test you had above.

In another window, track IOPS using iostat -dxk 1, summing the r/s and w/s columns OR using IBM's nmon tool with the D option to track the Xfers column (which is essentially the sum of iostat's r/s and w/s).

Here's nmon output from a heavy sequential read using bonnie++ -u root -n 64:100000:16:64 (run from within the target directory). At this point, we're showing ~3200 IOPS while reading at about 258 Megabytes/second on a 6-disk RAID 1+0 array of 15k RPM SAS drives.

- Disk I/O -----(/proc/diskstats)------- all data is Kbytes per second ---------------------------------------------
|DiskName Busy    Read    Write       Xfers   Size  Peak%  Peak-RW    InFlight                                     |
|iss/c0d0 100% 264571.1    112.3KB/s 3238.7  81.0KB  100%  340584.5KB/s   2                                        |
|s/c0d0p1   0%      0.0      0.0KB/s    0.0   0.0KB    0%       2.0KB/s   0                                        |
|s/c0d0p2   0%      0.0      0.0KB/s    0.0   0.0KB   99%    1022.4KB/s   0                                        |
|s/c0d0p3   0%      0.0      0.0KB/s    0.0   0.0KB  100%    3636.5KB/s   0                                        |
|s/c0d0p4   0%      0.0      0.0KB/s    0.0   0.0KB    0%       0.0KB/s   0                                        |
|s/c0d0p5   0%      0.0      0.0KB/s    0.0   0.0KB    0%       0.0KB/s   0                                        |
|s/c0d0p6   0%      0.0      0.0KB/s    0.0   0.0KB    0%       0.0KB/s   0                                        |
|s/c0d0p7   0%      0.0     41.9KB/s    7.5   5.0KB  100%   16103.5KB/s   0                                        |
|s/c0d0p8   0%      0.0      0.0KB/s    0.0   0.0KB   79%     147.8KB/s   0                                        |
|s/c0d0p9 100% 264571.1     64.4KB/s 3230.2  81.0KB  100%  340538.5KB/s   2                                        |
--------------------------------------------------------------------------------------------------------------------

Best Answer

Related Solutions

Linux Bash – How to Sort du -h Output by Size

Linux – How to interpret iozone values

Related Topic