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RLP in VNX?
Hi All,
I used snapview snapshots in emc clariion with Reserved Lun Pools. I want to know does EMC VNX series using reserved lun
pools when taking snapview snapshot? what happen if RLP's space got saturated, whether snapview session continue or not? kindly suggest me on this.
etaljic81
1K Posts
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July 1st, 2013 07:00
Main difference:
Min/max values are different. Certain restrictions also apply (pool LUNs, traditional LUNs, etc.). Take a look at the white paper Rainer posted.
etaljic81
1K Posts
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June 24th, 2013 06:00
Yes, VNX still uses the RLP for Snapview Snapshots. VNX Snapshots don't use the RLP but Snapview Snapshots do.
Snapview Sessions will not continue is the RLP space runs out.
Dhakshinamoorthy
174 Posts
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June 24th, 2013 08:00
Ernes Taljic,
can you elaborate difference between snapview snapshot vs snapshot?
Rainer_EMC
8.6K Posts
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June 24th, 2013 09:00
See the white paper
http://www.emc.com/collateral/software/white-papers/h10858-vnx-snapshots-wp.pdf
zhouzengchao
2 Intern
2 Intern
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1.4K Posts
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July 10th, 2013 18:00
Hi Dhakshinamoorthy.B
For your questions:
(1) Yes, VNX snapview snapshot still use reserved lun pools when you start a snapshot session on a source lun.
(2) The snapshot session which causes saturation on the reserved lun pool will be stopped. Other sessions will still run until they are also going to be out of reserved lun space.
hope that's helpful!
kelleg
4.5K Posts
1
July 17th, 2013 12:00
Extra point about the Reserve LUNs Pool - with raid group LUNs, best practice is to create a raid group(s) that is only for RLP LUNs - no user LUNs. Then you add these LUNs to the Reserve LUN Pool. When you use these RLP LUNs, the RLP LUN will get trespassed to the same SP as the source LUN. With raid group LUNs, there is no issue with trespassing the LUN to a different SP.
With Pools, if you use a Pool for the RLP LUNs, just as with raid group LUNs, you should use a separate Pool for RLP LUNs with no user LUNs in the Pool. As with raid group RLP LUN, when a snap session needs an RLP, the LUN will trespass to the SP that owns the source LUN. In Pools, it is not good practice to trespass LUNs.
I would recommend that for RLP LUNs, you continue to use the Best Practice for RLP - separate raid groups, no user LUNs, if more than two raid groups, put the LUNs into each Raid Group in alternating number sequence - that way, each new RLP that is assigned is taken from the different raid group (not completely, but mostly).
glen
GearoidG
251 Posts
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July 17th, 2013 12:00
And another note try to make sure the RLP luns are all of the same size
Gearoid
kelleg
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July 30th, 2013 14:00
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glen