Topic
  • 4 replies
  • Latest Post - ‏2013-05-10T00:18:41Z by tuscani
tuscani
tuscani
3 Posts

Pinned topic 3650 M3 RAID Question

‏2013-05-09T21:32:33Z |

One of my M3s has the M5015 controller with a 500gb x 5 RAID5. Can I create a new RAID5 in the other three slots with three 600gb drives? 

I assume I can, but my concern is also woth the Online Capacity Expansion feature.. I don't want the existing RAID5 to try and automatically use these 600gb drives. Thanks!

 

  • DaveQ
    DaveQ
    132 Posts

    Re: 3650 M3 RAID Question

    ‏2013-05-09T21:54:55Z  

    Hi Tuscani,

    You can create a new 3 x 600GB RAID 5 array using the 3 additional drives, and create a new virtual disk (LUN) on that new array.

    The existing RAID 5 array is independent; capacity expansion only occurs if you tell it to, and assuming you added the 3 new drives to the existing array.

     

    Dave

     

  • tuscani
    tuscani
    3 Posts

    Re: 3650 M3 RAID Question

    ‏2013-05-09T22:29:52Z  
    • DaveQ
    • ‏2013-05-09T21:54:55Z

    Hi Tuscani,

    You can create a new 3 x 600GB RAID 5 array using the 3 additional drives, and create a new virtual disk (LUN) on that new array.

    The existing RAID 5 array is independent; capacity expansion only occurs if you tell it to, and assuming you added the 3 new drives to the existing array.

     

    Dave

     

    Great news..

    This is a swing server that we are using to move VMs from SAN to local disk and then to a new datacenter and a new SAN. I just need more local disk for the weekend. :) But want to keep the existing RAID5 intact and left alone. Quick  follow-up.. once we power back up the server (it's ESXI 4.1 BTW) and copy data to the new LUN we can power it back off right away without issue right? I don't recall if there is any kind of wait period or heath check I should do since it's a brand new LUN.

     

     

  • DaveQ
    DaveQ
    132 Posts

    Re: 3650 M3 RAID Question

    ‏2013-05-09T23:18:03Z  
    • tuscani
    • ‏2013-05-09T22:29:52Z

    Great news..

    This is a swing server that we are using to move VMs from SAN to local disk and then to a new datacenter and a new SAN. I just need more local disk for the weekend. :) But want to keep the existing RAID5 intact and left alone. Quick  follow-up.. once we power back up the server (it's ESXI 4.1 BTW) and copy data to the new LUN we can power it back off right away without issue right? I don't recall if there is any kind of wait period or heath check I should do since it's a brand new LUN.

     

     

    There isn't a required waiting period other than the initialization of the virtual disk and whatever your own policies are. Once you create a datastore on the new LUN and successfully format with VMFS that's usually evidence enough that it's ready for use. After that it's entirely up to you when you power on/off the server.

    Depending on how long the server is unplugged - one thing you may notice, however, is that the array controller may complain that its battery charge is low (the M5015 has an onboard battery-backed cache accelerator). This will impact performance of any array on the controller until the charge is sufficient after power is supplied to the server again. If you encounter this - it just means the disks will change from write back to write through mode, meaning the cache accelerator is being bypassed since the battery can't offer the protection and performance of the cache accelerator while the battery charge is too low. Again, this is situational - depends on how long the server will be unplugged for and the charging capacity of the battery - and also if you set the virtual disk properties to "Write back with BBU". If the disks are set to "Write back with BBU" as their default policy, they will return to it after the charge is sufficient.

     

     

    Dave

     

     

  • tuscani
    tuscani
    3 Posts

    Re: 3650 M3 RAID Question

    ‏2013-05-10T00:18:41Z  
    • DaveQ
    • ‏2013-05-09T23:18:03Z

    There isn't a required waiting period other than the initialization of the virtual disk and whatever your own policies are. Once you create a datastore on the new LUN and successfully format with VMFS that's usually evidence enough that it's ready for use. After that it's entirely up to you when you power on/off the server.

    Depending on how long the server is unplugged - one thing you may notice, however, is that the array controller may complain that its battery charge is low (the M5015 has an onboard battery-backed cache accelerator). This will impact performance of any array on the controller until the charge is sufficient after power is supplied to the server again. If you encounter this - it just means the disks will change from write back to write through mode, meaning the cache accelerator is being bypassed since the battery can't offer the protection and performance of the cache accelerator while the battery charge is too low. Again, this is situational - depends on how long the server will be unplugged for and the charging capacity of the battery - and also if you set the virtual disk properties to "Write back with BBU". If the disks are set to "Write back with BBU" as their default policy, they will return to it after the charge is sufficient.

     

     

    Dave

     

     

    Got it. Thanks so much Dave!