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Change to Raid 5 ?

Hello ,

I have a FAS2020 with 6 disks of 500GB. It is now on raid_dp configuration, how can i change it to raid 5 ?

Can i have raid 5 configuration with just 4 disks ?

thank you

Re: Change to Raid 5 ?

As far as i know you can only use RAID4 or RAID6 (RAID-DP). RAID5 is not an option. Check out the specs here http://www.netapp.com/us/products/storage-systems/fas2000/fas2000-tech-specs.html

Acsysam.san wrote:

Can i have raid 5 configuration with just 4 disks ?

Yes but not on a Filer

Re: Change to Raid 5 ?

Just confirming RAID 5 is not an option with NetApp filers.  This is because the WAFL system works better with RAID4 / DP and changes the way you must think about RAID options and performance.

Bren

Re: Change to Raid 5 ?

Hey Sami,

Before you move to RAID 5 for performance or RAID 4 for disk savings, keep this in mind, RAID 6 offers added redundancy in allowing for two simultaneous drive failures.

Drive failures in general are correlated and if you absolutely don't want to lose your data, this is the safer of the two options.

You always have the risk of a second drive failing during the rebuild of data with a hot spare. (i have seen it!).

Anthony Feigl

Re: Change to Raid 5 ?

In the NetApp world you have two options:

Single Parity implemented as RAID4 (effictively equivalent to RAID5) as WAFL does not need to distribute Parity

and Dual Parity implemented as RAID-DP which complies with the RAID6 definition.

On any aggregate you can change from RAID-DP to RAID4  with a single instruction or click. The second parity disk becomes free and will be reused as a spare after zeroing, you can also add it into the aggregate as a data disk. Be careful - once added you cannot take it out again!!

You can also go from RAID4 to RAID-DP if you have enough spares (may need to check raidsetsize and maximums). This will take time as it builds the parity information.

In your environment simply go into the GUI and change you aggragate from RAID-DP to RAID4 (you will of course decrease protection), but in very small configurations this is often a satisfactory solution.

Re: Change to Raid 5 ?

Correction on my part...I did not mean that NetApp supports RAID 5.

I answered before my first cup of coffee

Anthony

Re: Change to Raid 5 ?

One small addition....you can change an aggregate from RAID-DP to RAID4 as long as it's RAID group size does not exceed the maximum for RAID4 on that platform.

Re: Change to Raid 5 ?

Read Section 5 of this paper for an overview of why WAFL and RAID4/RAID-DP were designed for each other vs using RAID5.

http://www.netapp.com/us/library/technical-reports/tr-3001.html

Re: Change to Raid 5 ?

For your purposes, RAID 4 = RAID 5 (i.e. ability to withstand a single disk failure).

And as noted, it's easy to change back and forth...just disk intensive so good to do after hours (I haven't changed from RAID4 to RAID DP or vice versa recently but have advised customers about it without their having any problems (easy enough they just did it themselves)).