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SyncRep
Hi all,
I have a question or two around SyncRep, and the potential limitations around it.
I understand there is a limitation of 32 volumes that can be "Syncrepped"? Is this correct?
Also, can I SyncRep volumes between dissimilar hardware, e.g. a PS6100 and a PS6500?
The idea is to eventually move our existing Data Center from one location to another, basically procuring new hardware and building the shell on the new site, Site B (including a vitual and physical environment), then replicating the data from Site A to Site B, and once done, firing up Site B and shutting down Site A.
That's the idea, at least :-)
Thanks a mill!
DELL-Joe S
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July 23rd, 2013 07:00
Yes 32 synchronous replications is the current maximum allowed.
Synchronous Replication writes volume data across two different storage pools in the same group, and yes this is hardware independent. There is a small performance hit with SyncRep (becase each write has to be sent to both pools/volumes) but typically spindle speed is negligible in this equation (PS6100 SAS is either 7.2, 10 or 15K disks syncing with 7.2K sata disks in the PS6500).
You didn’t mention how you wanted to migrate from the old PS group to the new PS group, but this can be done in several ways; backup/restore; create a new datastore in the new PS group, present the datastore(s) to your ESX servers, and then move your VMs to it; or use the standard replication (then promote the replication to a volume).
If you are looking to sync the existing volumes to the new PS group, then the standard replication method might be a workable solution for you (replicate, then promote the replica to a volume when the time comes). Of the three, moving the VM is the least disruptive with minimal downtime (copy VM files to the new datastore created in the new group).
-joe
srothman
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July 23rd, 2013 07:00
Excellent! In one reply you pretty much cleared up all my questions around the strategy to migrate the existing volumes. A Rockstar, indeed!
Thanks
Sebastian
Anonymous
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July 23rd, 2013 10:00
One side note. The PS4x00 series only array groups are limited to 8 sync rep volumes. Also there can only be two PS4x00 in a single group.
If you add a PS5x00 or PS6xxx series array in that group the limit is removed, but you still can only have two PS4x00 series members in one group.
Regards,
srothman
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July 23rd, 2013 13:00
Thanks Don,
This is in fact a 4-member PS6110 group I want to move to a PS6500 group, provided we can somehow get the required IOPS, which, at this point, seems to bite me a little bit.
To give you a little bit more background. At the moment I have an 8-member group, the 4 PS6110s for my back-office applications, cluster shared volumes, and SQL. This is configured in RAID 10. Then I have the 4 PS6500s in RAID 6 that host our centralized Exchange databases.
The idea is to buy 5 additional PS6500s, and then, for lack of a better term "consolidate" the 4 PS6110 members into a single member, and it's these volumes I need to replicate to reduce downtime to as little as possible. The Exchange environment is a like-for-like and we'll simply just move the databases, we can afford a certain degree of downtime on this service in any case.
Ultimately the idea is to reduce the physical footprint, considering we are moving our local data centre to a hosted environment and have limited rack space.
It's still early days and this is one of many scenarios we are throwing around.
I'll be posting more stuff here in the days to come... a lot more.
Thanks again
Sebastian
srothman
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July 23rd, 2013 14:00
Sorry, yes, all 10GbE :-)
Anonymous
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July 23rd, 2013 14:00
So you are mixing 10GbE and 1GbE in the same group? In the same pool? I'm hoping you mean 6510s?
Anonymous
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July 23rd, 2013 15:00
How many connections are in the current pool?
also the limit on members in a pool is 8. How many members are in your current pools?
srothman
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July 23rd, 2013 23:00
Currently we have 4 members across two Exchange Pools, and then the 4 back-office members are across two pools.
The number of connections per pool is as follow:
BO Pool 1 - 254 (3 members)
BO Pool 2 - 44 (1 member)
Exchange 1 - 338 (2 members)
Exchange 2 - 335 (2 members)
I actually had it wrong before. I have 3 BO members in RAID 10, 1 BO member in RAID 6, not all 4 in RAID-10.