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Skaughty
Asked: 2010-01-28 06:41:36 +0800 CST

How to grow a hardware Raid 5?

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I have a Dell PowerEdge 2970. Currently it runs as a ESXi server with a handful of VM's on it. I have 3 300GB drives plugged in to it, and 5 open trays across the front. It is setup as a hardware Raid5 from the factory. My question is if I start running low on disc space, can I just add on by pushing another hard drive into a empty slot, or will I need to back everything up and rebuild the array? If I can't just plug in another hard drive, would it be better to add 3 more drives, and build a second Raid5 to avoid losing any data that I have

dell vmware-esxi raid5

4 Answers

  1. The simplest thing to do might be to create a new RAID5 array and add it to the VM datastore as a new extent.

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  2. Best Answer

    I couldn't disagree with joeqwerty more to be honest. You don't mention which controller you have but all of the PERC 5 and 6 cards can perform live array expansion, although I'd be strongly tempted to fully backup your volume first. This way your new drive/s will become part of the R5 array and so will be able to survive a single disk failure. If you simply add another extent then in the event of losing a disk you stand a good chance of losing the whole VMFS datastore (the risk lessening if you're on ESX/i v4), plus expanding the array to 6 drives gives you 300GB more space than two 3 drive arrays.

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  3. To anyone else looking at this:

    On the older PERC 5 cards you could just pop the drives in and run a reconstruction in the RAID BIOS to add capacity or do a Raid Level Migration (RLM)

    On the PERC 6 you'll need to install the Open Manage Server Administrator. It takes a few extra steps when installing on ESXi, but it's worth it. You can expand a live array without any interruption in service. Although be aware that it does take a looooonnnnnggg time to rebuild the array after adding a drive (plan 4-6 hours at least), and during the rebuild you'll have degraded service.

    1. Shut down all hosts and install OMSA, then enable CIM using the steps outlined -> OMSA install on ESXi
    2. Then in order to access OMSA install the Managed Node Admin Tool on a separate station. (Can’t just use htps://server:1311)
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  4. Depends on the RAID controller to grow the volume and depends also on the OS to resize the partition and grow the filesystem. Check the documentation for your RAID controller and the documentation about VMFS.

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