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CX3-20 Arrays Raid Configuration
I have recently come onto a new site where there is a CX3-20 san, one of the biggest problems I have discovered is that Shelf 0, disks 0->13 are joined togeather in the same Raid5 disk group, and disk14 is the hot spare, I believe this is bad practice having the FLARE code a part of any other raid group plus there are multilps database products running on these disks too. If this is true then the 30GB of space the flare code takes up per disk is then lost space on the 9 additional disks in the group, just like parity.
AranH1
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June 13th, 2007 08:00
Yes you are right, that configuration wastes space, as drives 5-13 in the RAID group are only using part of the total capacity of the drive.
And because drives 0-4 are the cache vault drives (as well as the FLARE database and PSM LUN) it is not recommend to host LUNs there that will generate significant I/O because of the impact that will have on the cache vault peformance.
Do you have the option to migrate the LUNs in that RAID group to other disks? You could then unbind that RAID group and rearrange the grouping of disks in the first enclosure in a more logical manner.
Aran
DGM3
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June 13th, 2007 14:00
well as the FLARE database and PSM LUN) it is not
recommend to host LUNs there that will generate
significant I/O because of the impact that will have
on the cache vault peformance.
Discussion and recommendations regarding the first five drives can be found in the "Vault and PSM Effects" segment of the Best Practices paper at;
http://www.emc.com/techlib/abstract.jsp?id=1733
Starts at the bottom of Page 31 in the current (Release 24) edition.
Regards,
DGM
ThomasCarroll
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June 14th, 2007 06:00