Datastore array setup - RAID10 vs RAID5

[eversys]

I would like to have the following 4 virtual machines on our ESXi server:

- Windows SBS 2003 (DC, Mail, file/print for approx. 60 users)

- Windows Server 2003 Standard server (Document management)

- Windows Server 2003 with Datev (SQL DB)

- Windows XP Pro

- (in the future...) Windows Server 2008 Standard

I  was thinking of setting up a RAID10  using 4 x 600GB SAS HDDs giving me  a 1,2TB for the datastore - however, due to the nature of RAID10, I  would lose 50% of space! A RAID5 using the same 4 x 600GB HDDs would  give me 1,8TB.

I would appreciate any feedback regarding RAID10 versus RAID5 for this scenario. Many thanks.

[ITThies]

If you don´t plan to use that much of storage capacity, use RAID10.

You are using just 4 HDDs so there is not much IO performance to get out of the configuration. RAID10 can help you to raise the performance niveau due to the mirroring.

You are planning to virtualize a database too. Thats another fact to me for using RAID10 configuration

[eversys]

Thanks for your quick reply ITThies. Yes, space could be in issue in the fture. If we had more HDDs (i.e. 8 x 300GB instead of 4 x 600GB) - would you say that RAID10 would then be better than a RAID5? In the end, the datastore space for RAID10 would remain the same (1,2TB) and for RAID5 increase to 2,1TB.

[schepp]

The answer is like always: It depends...

It depends on what exactly you want to do. A RAID 10 will be faster at reading operations, while a RAID 5 will be faster at writing.

If your db doesn't experience any bottlenecks with a RAID 5, I'd choose that because of the larger space to use. We run several MySQL DBs on RAID 6 and they work fine because they are not that I/O heavy.

To come back to your HDD question (8vs4): A RAID 10 with 8 HDDs can be compared at writing speed with a RAID 5 with 5 HDDS. Reading is still faster of course. So, how I/O heavy are your applications and are you willing to spend as much money for 1,2TB as for 2,1TB?

Regards

[ITThies]

I would always prefer to use RAID10 configuration. If you need more space, add additional disks.

RAID10 is much slower in DB performance and if you are planning to have that amount of users on your environment, you should spend that extra money

[schepp]

M. Thies wrote:

RAID10 is much slower in DB performance

Guess that is a typo?

M. Thies wrote:

and if you are planning to have that amount of users on your environment, you should spend that extra money

He mentioned 60 users, which is quite a small amount..

[ITThies]

Jepp - my fault.

RAID10 is for sure faster and not slower for DB performance

[hafeezpashamoha]

A RAID 10 will be faster at reading operations, while a RAID 5 will be faster at writing.  In some cases, RAID 10 offers faster data reads and writes than RAID 5 becuase it does not need to manage parity.

To make picture clear, I'm putting RAID 10 vs RAID 5 configuration for high-load database, Vmware / Xen servers, mail servers, MS - Exchange mail server etc:

RAID Level	Total array capacity	Fault tolerance	Read speed	Write speed
RAID-10 500GB x 4 disks	1000 GB	1 disk	4X	2X
RAID-5 500GB x 3 disks	1000 GB	1 disk	2X	Speed of a RAID 5 depends upon the controller implementation

You can clearly see RAID 10 outperforms RAID 5 at fraction of cost in terms of read and write operations.

[schepp]

hafeezpashamohammed wrote:

RAID Level	Total array capacity	Fault tolerance	Read speed	Write speed
RAID-10 500GB x 4 disks	1000 GB	1 disk	4X	2X
RAID-5 500GB x 3 disks	1000 GB	1 disk	2X	Speed of a RAID 5 depends upon the controller implementation

You can clearly see RAID 10 outperforms RAID 5 at fraction of cost in terms of read and write operations.

Sorry, but I can't see anything "clearly" in your table.

"at fraction of cost"? How is a RAID 10 with 4 HDD much cheaper than a RAID 5 with 3 HDD? Don't tell me the controller, because you'll need that for both arrays