RAID 6 performance

X

xxEIEIOxx

2[H]4U
Joined
Feb 1, 2008
Messages
2,276
I am going to be building a new server. We are going with 4 SAS drives. My issue is to decide if we will be using all 4 in a RAID 6 array, or 3 in a RAID 5 with a spare. I am aware of the greater data security of RAID 6, but only have hands on experience with RAID 5. Would a 4 disk RAID 6 array perform as well as or better than the 3 disk RAID 5?
 
Usually performance with RAID6 is slightly less than RAID5 however depending on your application it may be negligible. If data integrity is more important then use RAID6. Most commonly RAID6 is used for large arrays where you are statistically more likely to encounter near simultaneous failures within the same array. For instance, the company I work for sells a piece of nearline storage that has 48 drives. The arrays are made up of more than 8 drives so we choose to take advantage of the RAID6 capability.
 
Shaggy3zx said:
Usually performance with RAID6 is slightly less than RAID5 however depending on your application it may be negligible. If data integrity is more important then use RAID6. Most commonly RAID6 is used for large arrays where you are statistically more likely to encounter near simultaneous failures within the same array. For instance, the company I work for sells a piece of nearline storage that has 48 drives. The arrays are made up of more than 8 drives so we choose to take advantage of the RAID6 capability.
Click to expand...

Thanks. This will be a 3 or 4 drive array running Server 2003 and SQL Server 2005. It will be used as a database server. Anything will probably be an improvement over the single drive machine we have now. I'm more leaning towards the RAID 5 with 3 disks and a spare drive. On the other hand, if 4 drives in RAID 6 would run as fast as 3 drives in RAID 5, it would be more worry free.
 
If space is not an issue, I think raid 10 would give you better performance and you would have to lose 2 drives to lose the array.
 
newdamage1 said:
If space is not an issue, I think raid 10 would give you better performance and you would have to lose 2 drives to lose the array.
Click to expand...

Good point, it would be faster. I'll have to see how the boss feels about spending $1,000 on HD's and losing half of the space. Though I think he would prefer the speed, which is the only reason we are building a new server anyway.
 
With a 4-drive R6 you will lose half the space anyways. R6 = N-2
 
You must log in or register to reply here.
Back
Top