Re: [SLE] is Raid 1 (mirror) so slow ?

Arie Reynaldi Z wrote:
I'd like to get more stability and fast recovery for my server. So i
decide to make RAID 1 (mirror) using 2 SATA hd, since using raid 1 i
almost dont have to worry about hardisk failure.
I want to use RAID 5 using 3 HD but this will cost me more. The
server will running java using tomcat, and mysql db. But our vendor
said that using RAID 1 is slower then using 1 HD. Is this true ? If i
use as application server using database, would be enough ? Another
thing, I use softraid from yast.

RAID 1 is actually faster when reading, because read requests can be satisfied from both disks.

It is a bit slower when writing, but only a few %.

The real-world performance also depends on your file system and on your RAM and the resulting filesystem cache. (Many I/O requests can be delivered from the cache.) On my mirrored SATA disks with ext3, I get about 30 MB/s when I really write to the disks. To get faster I/O, I would need to use striping massively. (Always remember to stripe the mirrored disks, and not the other way round.)

But you can do some tests for yourself, if you can set up a test system with mirroring: install bonnie++ and check the performance before and after mirroring.

All in all, all our disks are mirrored (softraid 1). With current disk prices, that's easy to do.

Best,
Joachim

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Joachim Schrod Email: jschrod@xxxxxxx
Roedermark, Germany

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