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1769
November 23rd, 2011 05:00
journal volume with Raid Group
Hi
I need to create 300GB journal volume on CLR CG
How i decide what Raid Group type and disks i need to create the Journal volume on my prod and dr clariion?
Can I put on this RG all my journal volumes?
Do i need to cretae small volume or i can use on big volume per journal?
Moshe
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bergec
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November 23rd, 2011 13:00
I assume this is a CX or VNX backend (Raid Groups)
This is my understanding on how it works with CX/VNX when creating or expanding the JVOL for a given CG
Be careful not to create stripe on stripes
For example if during the initial creation of the JVOL you present RP with 2 luns from RG0 and 2 luns from RG1 and all 4 luns are 100gb, then RP will stripe the in one volume and you will end up with 2 LUNs from each RG striped together (same if the luns are within 15% of size). In that case you would be better to create one 200gb lun on RG0 and another 200gb lun on RG1
If later on you decide to expand the JVOL, then RP will see new LUNs and repeat the same method in order to create a new stripe, but that new stripe will be concatenated with the previous one (there will not be a full re-stripe even though the new LUNs that you add to the Journal are the same sime as the previous one)
Claude
ankur.patel
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286 Posts
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November 23rd, 2011 07:00
How i decide what Raid Group type and disks i need to create the Journal volume on my prod and dr clariion?
You should use Raid 5 as the raid type since the IO size is large and sequential in nature
Can I put on this RG all my journal volumes?
Yes you should dedicate raid groups for journals because their IO size (256KB+) is larger than most applications, so keeping this workload seperate makes sense.
Do i need to cretae small volume or i can use on big volume per journal?
creating smaller volumes , for example 3x100GB or 2x150GB makes sense since when you grow the journal you should grow it by adding another 100GB or 150GB component. If you have one large volume that is 300GB you will have to grow it by that large amount.