Performance Increase For unRAID.

By | March 23, 2008

There is a thread at the unRAID forums here that discusses increasing the read-ahead buffer in unRAID from the default 256KB to 2MB can drastically increase performance. I hadn’t tried it since I’m very new to unRAID and not very proficient in Linux, so I was unable to comment…until now.

A few minutes ago I felt adventurous and decided to do it. Effects are immediate, so there was no rebooting involved and it appears as there is also no risk involved…it either helps or it doesn’t.

Long story short, I test it at the default with a 2.1GB file and found I was transferring at 24.8MB/s. Not terrible for a light media server, but not that great either. I then, following the instructions from the thread, put in the following for each of my drives:

For disk1:

root@mediasvr:~# blockdev --setra 2048 /dev/md1

For disk2:

root@mediasvr:~# blockdev --setra 2048 /dev/md2

After testing again, I found that I had gone up to 61.4MB/s. Astoundingly, almost a 250% increase in performance.

Needless to say, I used an entry for the Go script to execute this modification at each boot. Please visit that thread for any discussion. Otherwise, your comments here are always welcome.

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