RAID5 slow write at ~3MB/s

K

Korialstrasza

Gawd
Joined
Jan 21, 2004
Messages
561
Hey, I have 3x 300gb PATA, 7200 8mb Cache HD's setup with an LSI Logic MegaRaid i4 with the settings:
Raid5
3 Stripes, 32kb stripe size
Writethru
DirectIO

Should I only be writing about 3 MB/s? That seems kind of slow. The other spare 80gb on the system gets ~50MB/s across my gigabit network.

Thanks for any tips.
 
Your 80gb drive wont have anywhere near 50mbytes/s write speed. fyi

Your raid write speed is slow though.
This will be at least partially due to not using the write cache.
You should enable it and see what the performance will be.
If that corrects it, then you know why.

You can test the speeds properly using HDTach or HDTune.
 
I'll try that, thanks.

It does get around 50 read, sorry I didn't make that more clear. It only gets about 15 MB write across the network. Should I be content with that?
 
Yeah 15MB/s is about right assuming you have a gigabit network.
 
I ran HDTune and here are the results.

Does this mean the logical drive is fine, and that I'm only getting 3 MBps write because of the network? I get around 50 MBps read across the network from it, just slow write.

I turned on write caching too.

my.php
 
Ah I forgot they dont measure write speed (unless you purchase HDTach)
goto this page
http://www.benchmarkhq.ru/be_hdd.html
and find Drive Speed Checker

This little tool tells you the overall write speed, I assume its an average.
It will give you the ballpark write speed.
 
You must log in or register to reply here.
Back
Top