RAID Question

damir

I am wondering whether I would get better performance from RAID 10 with 6 disks and with one database file, or having 3 database files RAID 1 with 2 disks each. This is using Navision Database Server.
Has anybody tried this combinations?

TIA,
Damir

kriki

I never tried it. But I heard a rumour that 3 times RAID1 is better than 1 RAID10 with 6 disks. So I can't guarantee it is better.
The advantage with RAID10 is that you have 1 BIG logical drive and 1 BIG DB-file. This is advantageous for administrating, because you only have 1 DB-file.

bbrown

In the situation you describe, assuming the same hardware, I would say that the 3 RAID 1 sets would provide better performance. Navision uses a separate process to manage the I/O for each database file. In your RAID 10 example a single process would be tasked with 100% of the I/) demand. In the RAID 1 example, the load would be shared among the 3 processes. SQL has similar functionality by splitting filegroups across multiple physical files.

The bottleneck for any one of the processes becomes how fast the disk system can service the request. One interesting approach is to combine the two solutions on large databases. That is create multiple database files, and place each on its own RAID 10 array. The configuration possibilities are limited only by imagination and budget.

Waldo

I can confirm this.

In my former company, they (not me) did some kind of benchmark and 3 times RAID 1 seemed slightly better. (they did it with 4 sets and a database of 40GB).

bbrowns explanation confirms it again ...

Waldo

Actually, I posted this question 3 years ago...
RAID 0+1 or RAID 1?

kine

If you are talking about Native DB, more files on more physical volumes is better. Of course, do not forget that you need not overload the RAID processor... (control unit has limited command queue)...

damir

Thank you all very much.
I thought that one RAID10 would be better solution, since all job with splitting and merging parts of data is done by controller.
However, it looks like Navision Server is doing admirable job.

Waldo

Never underestimate the power of the native ... 8)