Home > Dell, Equallogic, ISCSI, Storage, vSphere > HOWTO: Migrate RAID types on an Equallogic array

HOWTO: Migrate RAID types on an Equallogic array

I’ve run into a situation where I have a need to change RAID types on an Equallogic PS4100 in order to provide some much needed free space.  Equallogic supports on the fly migration as long as you go in a supported migration path:

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  • RAID 10 can be changed to RAID50 or RAID6
  • RAID 50 can be changed to RAID6
  • RAID 6 cannot be converted.

By changing from RAID50 to RAID6 on a 12x600GB SAS unit, we can go from 4.1TB to 4.7TB, which will help get some free space and provide some extra life to this environment. 

1) Login to the array, and click on the MEMBER, then MODIFY RAID CONFIGURATION:

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Note that the current RAID configuration is shown as “RAID 50” and STATUS=OK.

2) Select the new RAID Policy of RAID6:

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Note the change in space – from 4.18TB to 4.69TB, and a net change of 524.38GB, or about 12% extra space.  Click OK.

3) During the conversion, the new space is not available – which should be expected:

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After the conversion, the space will be available.  Until then, the array status will show as “expanding”, as indicated.  Click OK.

4) You can watch the status and see that the RAID Status does indeed show “expanding” and a PROGRESS of 0%:

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After about 7 hours, we’re at 32% complete.  Obviously this is going to depend on the amount of data, size of disks, load on the array, etc.   But we can sarely assume this will take at least 24 hours to complete. 

5) When the process completes, you will see that the RAID Status is OK as well as the MEMBER SPACE area will show free space:

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Understandably, you now need to use this space.  It won’t be automatically applied to your existing Volumes/LUN’s, so you’re left with two obvious choices – grow an existing volume or create a net new one.  As it is expected creating net-new is understood, I’ll demonstrate how to grow an existing volume.

6) On the bottom left of the interface, select VOLUMES:

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Then in the upper left, expand the volumes:

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Select the volume you wish to grow.  I’ll choose EQVMFS1.

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Click MODIFY SETTINGS and then the SPACE tab.  Change the volume size accordingly.  It does indicate what the Max (1.34TB) can be.  I would highly recommend you reserve at least some small portion of space – just in case you ever completely fill a volume you may need to grow it slightly to even be able to mount it.  Even if small, always leave an escape route. 

Click OK.

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You are warned to create a snapshot first.  As these volumes are empty, we won’t be needing to do this.  Click NO.

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Note the volume size now reports as 1.3TB.

7) Next, we go to vSphere to grow the volume. 

Right click on the CLUSTER and choose RESCAN FOR DATASTORES:

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Next, once that completes (watch the Recent Tasks panel), select a host with the volume mounted and go to the CONFIGURATION -> STORAGE tab.  Right click on the volume and choose PROPERTIES.

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8) Click INCREASE on the next window:

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Then select the LUN in question:

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NOTE that in this example, I’m upgrading a VMFS3 volume.  It will ultimately be blown away and recreated as VMFS.  But if you are doing this, you will see warnings if you try to grow about 2TB, as it indicates.  Click NEXT.

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Here we can see the existing 840GB VMFS as well as the new Free Space of 491GB.  Click NEXT.

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Choose the block size, if it allows you.  Again, this is something you won’t see on a VMFS5 datastore.  Click NEXT and then FINISH.

9) As this is a clustered volume, once complete, it will automatically trigger a rescan on all the remaining cluster hosts to pick up the change:

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You don’t have to do anything for this to happen. 

And that’s really about it.  You have now expanded the RAID group on the Equallogic, and added the space to an existing volume.  Some caveats of course to mention at this point:

  • Changing RAID types will likely alter your data protection and performance expectations.  Be sure you have planned for this.
  • As noted before, once you go RAID6 you can’t go anywhere from there without a offload and complete rebuild of the array.
  • If you hit the wall, and got back ~ 10%, this is your breathing room.  You should be evaluating space reclamation tactics, new arrays, etc.  This only gets you out of today’s jam.
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Categories: Dell, Equallogic, ISCSI, Storage, vSphere
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