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RAID 1 or 5

Occasional Visitor

RAID 1 or 5


I plan to build a VMWare server (ESX Server) out of an existing ML350 with Dual 2.2Ghz Xeon's and 3GB of RAM. The machine has a Smart Array 5302-128 RAID Controller. I have two 36GB U3 10K drives where I will install VMWare in a RAID 1 array. I also have several 72GB U3 10K drives where I will put my Virtual Machines. As I want to be able to get the best disk performance from these drives I am wondering if it would be better to build them in a RAID 1 or RAID 5 array. Up to four Virtual Machines will have their Virtual Disks on the 72GB drives and while no one machine is undergoing a heavy load I am interested to know peoples thoughts and recommendations to provide the best performance. I have 5 x 72GB drives so could do either RAID 1, RAID 1+0 or RAID 5. I understand the benefits of one over the other in terms of redundancy etc but wanted to know thoughts on performance.

Ivan Ferreira
Honored Contributor

Re: RAID 1 or 5

In terms of performance, your best option is to create:


1- RAID 1+0
2- RAID 1
3- RAID 5

Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Ernest Ford
Trusted Contributor

Re: RAID 1 or 5

I know you didn't ask this, but have you considered your space requirements - some RAID implementations are notoriously inefficent when available space is considered.

With 5x72GB disks, a RAID5 array will give 288GB of available space, a RAID 1 will provide 144 GB, and a RAID 1+0, 72GB

RAID1 and 1+0 must be configured using even numbers of disks, RAID 5 does not have this limitation.
Steven E. Protter
Exalted Contributor

Re: RAID 1 or 5


If you wish to do heavy write i/o Raid 1 or Raid 10 will be faster.

With raid 5 all writes have to be made to up to 45 different disk locations using the normal disk parity. That takes times and really slows down write intensive systems.

For data mines and systems that do not incur heavy update, Raid 5 can be faster (it surely saves 50% of disk space use) and make such systems more economical.

Steven E Protter
Owner of ISN Corporation