Topic
1 reply Latest Post - ‏2013-01-31T13:01:22Z by djole_k
SystemAdmin
SystemAdmin
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Pinned topic Storwise V7000, Spread an array across SAS chains or not?

‏2013-01-30T13:57:13Z |
Hi,

Let's say I have one V7000 controller and one expansion unit. I need to configure two arrays, each containing a set of 10 HDD's in raid5. Does it matter if the array's are in the same SAS chain or not? I.e:

1: Drive slot 0-4 in each enclosure for Array 1 and Drive slot 5-9 in each enclosure for Array 2.
or
2: Drive slot 0-9 in one enclosure for Array 1 and Drive slot 0-9 in the other enclosure for Array 2.

Thanks for any replies! /Joakim
Updated on 2013-01-31T13:01:22Z at 2013-01-31T13:01:22Z by djole_k
  • djole_k
    djole_k
    41 Posts
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    Re: Storwise V7000, Spread an array across SAS chains or not?

    ‏2013-01-31T13:01:22Z  in response to SystemAdmin
    It is possible for some kind of RAID configuration. One example is a "Balanced RAID 10" for SAS disk. For the usage of SSD's it is recommended to spread the high performance devices across the backend. (http://pic.dhe.ibm.com/infocenter/storwize/ic/topic/com.ibm.storwize.v7000.640.doc/svc_presets_09271645.html)

    But here's another theory: You can build Arrays on each SAS-Chain. The result will be mdisks on both SAS-Chains. Now you put this mdisk in a storage pool and you have spread the Space there your Volumes will be places over both chains. Per default the extents of a volume will be "striped" over all mdisks in an storage pool. In this case you do not spread a single array, but each volume over all resources.

    I think it's also easier to handle the IO's (internal) when one mdisk (=array) belongs to on SAS-controller/chain.

    In both ways you will use all resources of the V7000. But it's up to you, how you will configure your system.