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VNX Write Intent Log Disk Amount
Hello,
I have got a question concerning VNX Write Intent Log (WIL) performance.
I know that WIL on pool LUNS is not supported and WIL on VAULT drives not recommended.
The machines are two VNX using MirrorView/S.
How much SAS disks do I have to put in a RAID group to have enough disk performance for WIL. Is a RAID-1 with 2 SAS 10K disks enough? Are there rules of thumb or a calculator for this issue?
regards
Robert
sameek
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January 30th, 2015 04:00
Hi
Please check Kb article given below this may help you
https://emc--c.na5.visual.force.com/apex/KB_BreakFix_1?id=kA1700000000MdD
Thanks
sameeksha
dynamox
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January 30th, 2015 04:00
isn't there a typo in that KB?
The WIL is stored on a pair of 2 GB LUNs (one for each SP) at current levels of VNX OE, although with older levels of flare, these can be as small as 128MB. These can either be RAID-group based LUNs, metaLUNs or Thick Pool LUNs. The same applies to CPL (Clone Private LUNs).
Virtual Provisioning LUNs are not supported for the WIL
r_spiess
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January 30th, 2015 10:00
What about disk performance for WIL? What kind of RAID group configuration is needed for WIL?
Is RAID 1+1 R1 enough or do I need 4+1 R5 or 8+1 R5 or 4+4 R1/0 ? I do not want to use more disks for that RG as necessary, because RG will only be used for WIL not for other LUNs. So less is more :-)
regards
Robert
dynamox
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January 30th, 2015 13:00
I am getting reading to configure MirrorView for a brand new set of VNX. At each site i have 4 x 300g 15k drives that will be configured into 2+2 R1/0 RG. Probably an overkill but i am not sure what to expect from WIL I/O numbers, this should suffice.