Making servers faster: RAID 1 vs RAID 5 performance differences
October 7th, 2008
To start this post off I thought that I’d initially go through the core differences between RAID 1 & RAID 5. I haven’t mentioned arrays without RAID because if you in any way value your data RAID is essential.
Jargon:
RAID: Redundant Array of Independent Disks
Array: A number of disks, normally connected to the same RAID Controller
RAID Controller: A dedicated piece of hardware which has the task of replicating data
Capacity – How does my RAID choice affect storage capacity?
RAID 1
Disks have to be set-up in identical sized pairs so x2 1TB drives will give you 1TB of space. If you want more you have to add additional pairs.
RAID 5
A minimum of 3 drives are required and the total capacity is the sum of all the drives, less the size of one of the drives. I.e. x3 1TB drives = 3TB – 1TB = 2TB useable.
Redundancy – Is one more redundant than the other?
RAID 1 offers redundancy in pairs where as within a RAID 5 configuration where any one drives can fail. In the event that a drive fails and is replaced in a RAID 1 array it the file system will run at around half speed until the all the data is recovered. Within a RAID 5 array as there are more drives to share the load the file system will run slower but not as slow as it would in the RAID 1 situation and by adding more drives to an array this performance reduction is reduced.
Performance – Which one is better?
RAID 1 limits the performance to the two drives which are in the array whereas with RAID 5 the load can be shared over a number of disks. So rather than just having two drives which are both writing for each operation it is better to be able to write/read to/from a number of drives.
While the gains do decrease as the number of drives increases a substantial difference in performance would be noticed between an array with 3 drives and say 8. There are cost implications to bear in mind however if it is performance is critical then these can become justifiable.
Isn’t RAID 5 slow?
It used to be the case that RAID 5 was slow however over the years RAID controllers along with everything else has evolved substantially and multi-drive RAID 5 arrays are now plainly faster than RAID 1 arrays.
If you have any questions about server performance or how to make your application faster please feel free to get in touch with us.
Entry Filed under: Managed Hosting
7 Comments Add your own
1. Brook | January 15th, 2009 at 7:24 pm
Hello,
We currently ran into our Server which has Raid 5 low Disk Space. We did clean up some data and change some settings. However so we do not run into this again we are considering purchasing a Raid 1 Network Storage. Then we would move our Y Drive information onto the Network Storage. Is this the best thing to do as in cost efficiency, security and protection against loosing data?
2. Duncan | January 19th, 2009 at 8:41 pm
Hi Brook,
it really depends on the situation. From what you’ve said this sounds like you’re looking at an office situation rather than a server in a datacentre.
I would suggest a NetGear ReadyNas if it’s for your office. If it’s for your datacentre it’s really dependant on use. If we could get some more details i.e. what it’s used for, amount of storage & how fast it’s growing, we could give you some more advice.
3. Chris Taylor | June 5th, 2009 at 8:38 pm
We have always used Raid 1, two mirrored drives for our main fileserver together with a backup and never had any problems. If we lose one drive on Raid 1 you have redundancy, if you lose two drives at the same time your data is lost, with Raid 5 if you lose two drives at the same time is your data also lost? even if you have a hot spare would it be any use if you lose two drives?.
4. Mark | July 5th, 2009 at 11:50 am
Hello,
We are working with video editing and as you know the raw video is take all the available spaces,
We need the best storage system to use it as storage and share NAS drive with the best configuration to keep the data protected and ultra fast.
what you suggest for us?
I read Raid 5 is good but, I don’t know about Raid 0+1 and 6 and 10 and other raid systems.
what is the fast without losing a lot of spaces?
5. admin | July 16th, 2009 at 4:20 pm
Netgear have a pretty good selection of NAS devices which support from 2 to a number of drives.
In terms of video edit data the RAID level you use won’t have much impact on performance.
For redundancy RAID5 with 3 drives can be superior to RAID1 with 2 drives, but it depends how you set it up. Ideally if you’re really worried you would take a backup onto a separate drive or onto a DVD/Tape.
6. Jon Slater | July 20th, 2009 at 12:34 pm
Re. RAID levels. RAID 10 speeds up both reads and writes unlike RAID 5 which is a bit slower on writes due to the parity calculation (although it speeds reads). The more disks you have in array, the more chance of 2 disks failing at the same time. RAID 6 protects against this and gives about 88% of raw capacity. RAID 6 is similar to RAID 5 in terms of performance and is good for data warehousing.
7. ColdFusion Developer | July 21st, 2011 at 11:37 pm
Thanks for the info. Do you have any references with actual benchmark tests of comparing read/write/access speeds comparing RAID 5 and RAID 1?
I haven’t found anything in my Google searches yet.
Leave a Comment
Some HTML allowed:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>
Trackback this post | Subscribe to the comments via RSS Feed