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not using all disks in disk group
DMX1000
I have a disk group 0 with 40 drives, same speed and size.
2 FA's, so each processor has 5 disks assign to it.
in theory I should be able to create a 5 member (RAID 5 7+1) meta lun from this group without worry about hypers wrapping across the same drives.
But when I created the 5 devices I noticed that only 32 disks were ued, so 2 members ended up sharing the same 8 disks.
when investigating the drives in SMC, I noticed 8 drives in DG0 that have never been used, they don't have any hypers on them and they're still at max free capacity, also they do not show any info such as vendor ID, product ID, Disk RPM...etc
any suggestion as to why this is happening?
thanks
ayakovenko
14 Posts
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April 22nd, 2010 05:00
During procees of device creation symmetrix tries balance not only by disks but by BE direcors too.
jliu2
82 Posts
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April 22nd, 2010 07:00
yup that's true, those 8 drives are spread evenly across all 8 processors
John Toner
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April 22nd, 2010 07:00
Can you create any 2-way-mir or RAID5 3+1 devices using these disks? If so, then I would guess that your 8 drives are not quite configured correctly in the backend.
jliu2
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April 22nd, 2010 08:00
would I have the ability to select the physical disks during a LUN creation? I thought I could only go down to the disk group level
perhaps this is something our CE can do?
dynamox
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20.4K Posts
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April 22nd, 2010 09:00
yeah ..CE's have more control with Symmwin in the bin file but still ..Symmwin will not allow your to add devices that do not satisfy all internal availability checks.
RobertDudley
448 Posts
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April 22nd, 2010 10:00
It is possible that the raid affinity is not correct for those last 8 disks. See primus emc225354.
Also disks with no hypers on them will show as n/a until a hyper is created on them. See primus emc225807.
RRR
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April 27th, 2010 01:00
You have 2 options:
Option 2 is probably the best option since then EMC has to write an official answer to this and they'll invoke the CE anyway if something has to be changed.
dynamox
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April 29th, 2010 11:00
What If you try 3+1 ..do they get placed on the first 8 drives as well ?
jliu2
82 Posts
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April 29th, 2010 11:00
yup I had my CE looked at our BIN file and sure enough discovered that 2 out of those 8 drives were on the same disk director bus, which caused them to ignored. But now I'm facing a new issue, now that the drives have been moved to right disk director, these 8 drives have become the preferred drives for anything I create in Group 0. Most the of the other drives have about 40 hypers and 38GB left in capacity. I tried to create 5 logical RAID5 (7+1) devs and all 5 devs ended up on those 8 drives, since they were is least used drives in the group. What's my best option right now to make sure all drives can be used in group 0? I know that symmetrix optimizer is able to move data between disk, but that's not an option for us at this point.
thanks
jliu2
82 Posts
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April 29th, 2010 11:00
neither ECC nor SMC is giving me the option to create RAID5 3+1
but I suspect the same thing will happen, basically I would have create a bunch of "buffer" devices before those 8 drives balances out with the rest of the disk gorup.
Also thought about moving them to a separate disk group, but that limits me to just nonmeta devices for that group to avoid disk wrapping. Are these major performance issues if I were to put devices from different disk groups with different drive speeds in the same meta?
RobertDudley
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April 30th, 2010 05:00
On a DMX1000 you can only create raid5 3+1 or Raid5 7+1 depending on the raid type setting in the bin file you cannot have both raid types on that array. On the V-max you can have any raid type you want to create. Raid-1 (mirroring) has no dependency like raid 5.
If you are able to create raid 5 7+1 then you cannot create raid 5 3+1 on a DMX1000 and vice versa; you can have one or the other not both.
dynamox
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May 5th, 2010 07:00
72+ you can mix 3+1 and 7+1
RRR
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5.7K Posts
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May 5th, 2010 07:00
Ah ok, it's been a while since I came accross a mix on 1 box.
RRR
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May 5th, 2010 07:00
I thought that being able to choose between either (3+1) or (7+1) was a pre enginuity 71 thing and that you can mix this in eng 71 and up ?
RobertDudley
448 Posts
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May 5th, 2010 12:00
A DMX1000 stops at 5671 code. DMX-3/4 started at 5771 and goes up, 5772, and 5773.