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nicoroy123_15c2b9
41 Posts
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October 30th, 2009 06:00
Striped VS Concatenated
Hi, in one of our DMX4, we have 5 Raid Groups of 300GB 10K drives (7+1).
Our device size is about 60GB (65200 ).
Now we are planning to move Exchange DB and VMWare stores to that area. Based on my undestanding, in a 5 raid groups scenario, striped meta should not go over META5, while Concatenated Metas could go over 5 but with an impact on perfromances since we are reusing the same raid groups in the meta.
So what would be our best config for Exchange and VMWare?
I hope my question is clear...
Our device size is about 60GB (65200 ).
Now we are planning to move Exchange DB and VMWare stores to that area. Based on my undestanding, in a 5 raid groups scenario, striped meta should not go over META5, while Concatenated Metas could go over 5 but with an impact on perfromances since we are reusing the same raid groups in the meta.
So what would be our best config for Exchange and VMWare?
I hope my question is clear...
1029
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Posted October 30th, 2009 13:00
Wrapping is generally not a good idea. If you have an option to stripe at the host, a good compromise would be to make 5 serial metas on your 5 raid groups, each 1/5th the size of the LUN you need, then combine these at the host level into one striped volume.1029
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Posted October 30th, 2009 13:00
Thanks Quincy.
With the striped volumes, the other problem I face is a maximum of Meta5 since I have 5 raid groups.
5 x 60GB will give me 300GB volumes, assuming that I want to make sure no raid group get used more than once in the same Meta.
I will need bigger volumes than that. This is what I have to figure out...1029
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Posted October 30th, 2009 21:00
unfortunately to stripe on windows host you have to use dynamic disk or Veritas storage foundation. Dynamic disk is not supported by MS clustering and storage foundation is big $$$.1029
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Posted October 31st, 2009 14:00
Quincy AFAIK concatenated meta are quite different from serial metavolumes... A concat meta is available through symconfigure while a serial can only be built using symwin. Now I expect a few more questions on serial metavolumes...1029
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Posted November 2nd, 2009 03:00
didn't we have a conversation about serial metas about a month (or two) ago ? All you said was: it's a bit of a secret... or something...1030
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Posted November 2nd, 2009 04:00
Serial meta volumes are something I asked for when we were trying to come up with tape library for Symmetrix. They are as close as you can get to a native large RAID5 volume as you can get. All the members in order down a raid group, concatenated down the same drives. We were making two 2TB volumes out of one 7+1 raid group and presenting them to the tape library units. These sorts of configurations can be good for large sequential operations without a ton of threads.1030
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Posted November 2nd, 2009 08:00
Now serial metavolumes don't have secrets...1030
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Posted November 9th, 2009 08:00
Ok, let say I cannot strip at the OS level and still need big volumes, which one would you choose between a striped meta that wraps around vs a concatenated meta?325
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Posted November 9th, 2009 08:00
concat for sure. With striping you need every symdev to sit on a separate raid group and with concat the performance impact when "reusing" the same raid groups isn't as high as with striping.
Quincy561
1281 Posts
1029
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Posted October 30th, 2009 07:00
You might not want to stripe that striped meta again at the host level.