Virtualization Tips » RAID http://www.virtualizetips.com Covering all things in your Virtual Data Center. We write VMware, Citrix & Microsoft from VDI to VMotion. VMware Tips Wed, 08 Sep 2010 14:41:24 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 Guide to choosing raid type on VMware ESX for beginners http://www.virtualizetips.com/2010/03/guide-to-choosing-raid-type-on-vmware-esx-for-beginners/ http://www.virtualizetips.com/2010/03/guide-to-choosing-raid-type-on-vmware-esx-for-beginners/#comments Tue, 09 Mar 2010 16:57:55 +0000 Brian http://www.virtualizetips.com/?p=108 For newer admins or those without a storage background, this is a common question that I hear often. What type of RAID should I use for my data stores to host Virtual Machines. This is not meant to be a high level storage best practice document. I’m just covering some basic details that should help new admins and SMB customers.

First thing you need to do is do some research on what type of servers you will be Virtualizing and what their IO needs might be. The main reasons for choosing different RAID levels will be performance and redundancy. Most people tend to lean towards RAID 5 which provides good performance with a high level of redundancy. See the chart below for some more details. You can also review some details from VMware here.

Summary of the different RAID types

Type RAID 0 RAID 1 RAID 1+0 RAID 5
Method Striping Mirroring Mirror and striping Stripe with Parity
Description The data is striped across all the disks in the set. Not true RAID because it is not redundant. Exact copies of the data are kept across paired disks or disk sets. A striped array whose segments are a mirror set. Not to be confused with 0+1 The data is striped across all the disks in the RAID set, along with the parity information needed to reconstruct the data in case of disk failure.
Performance Good. All IO is spread and no parity overhead Twice the read rate but writes occur twice Combines speed efficiency of the RAID 0 (stripe set) with a fault tolerance of RAID 1 (mirror). High read and medium write performance. A good balance of performance and availability.
Typical use Data you can afford to loose, such a pre-production, image/video editing. Data requiring high availability, such as accounting or payroll. Transactional type data such as database logs. File and application servers. Typically everything that does not have a specific requirement.
Parity Calculation None None None Yes
Redundancy None Yes Yes Yes
Minimum Disks 2 2 4 3
Storage Overhead 0% 100% 100% Capacity of one disk in the set. 33% for a 3 disk set.
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