April 10, 2009 at 12:29 pm
I have an old Hitachi SAN and a new EMC SAN. We are upgrading our core application to use SQL Server2008 instead of SQL2000. We have had some discussions on what is the best HA solution.
If I have 2 DL580 G5's (or something similar) and one is connected to the Hitachi SAN and the other is connected to the EMC SAN. Can I configure database mirroring for one database across the 2 different SANS?
I've been trying to read up on SAN's as much as possible and know they have built in features like san replication etc.
OR
Setup db mirroring using one SAN.
OR not use db mirroring and some other method.
I'm comfortable with database mirroring because I have implemented it it a couple other places using attached storage with IDENTICAL hardware.
What would you do for HA if you had 2 servers 2 SANS and SQL Server 2008?
April 10, 2009 at 12:38 pm
You need to do Database Mirroring between 2 instances of SQL, so in your case you should probably use your first option, one server attached to one SAn and the other server attached to the other SAN and setup the mirroring between the 2 servers.
You'd want to use the better hardware for your primary server.
The beauty of Database Mirroring is that both setups do not need to be identical.....
April 10, 2009 at 1:40 pm
i would migrate all data to the new SAN and setup database mirroring between the 2 instances. Decommission the old Hitachi SAN unless you have any real need to keep it running
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April 10, 2009 at 3:27 pm
Hello Here is my setup I am using IBM Netapp and SQL Server 2005
I have two servers my primary is connected to the san and acts as a principle while my secondary server sits as a mirror server; however, I am using snap mirror on the first netapp filer to write to the second netapp filer at my dr location
I am not sure about EMC but it should have similar options please let me know if you need more info
April 10, 2009 at 3:44 pm
Perry Whittle (4/10/2009)
i would migrate all data to the new SAN and setup database mirroring between the 2 instances. Decommission the old Hitachi SAN unless you have any real need to keep it running
I would keep the primary on the new SAN and the mirror on the old SAN. This way if you lose a SAN you don't lose both servers.
April 10, 2009 at 4:41 pm
Edogg (4/10/2009)
This way if you lose a SAN you don't lose both servers.
absolute rubbish, the whole point of a SAN is multi pathing and fail over. Chances are, if you lose the whole SAN you've lost all building power anyway so none of the kit will be functioning and will be about as useful as a chocolate kettle.
You could put the older SAN at your DR site and replicate the LUN's out to the DR SAN, instead of decommissiong old kit, re use it!
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"Ya can't make an omelette without breaking just a few eggs" 😉
April 10, 2009 at 5:04 pm
absolute rubbish, the whole point of a SAN is multi pathing and fail over. Chances are, if you lose the whole SAN you've lost all building power anyway so none of the kit will be functioning and will be about as useful as a chocolate kettle.
You don't necessarily have to lose building power to "lose" a SAN. If there is a write failure in the SAN cache the cache could become "pinned" to try and maintain data integrity. Granted, this doesn’t happen often especially if you have mirrored cache. I’m not trying to provoke an argument, just pointing out possibilities.
For true HA you need multiple paths to everything, SAN with separate switch fabrics, dual network paths on separate switches, dual network paths to your DR site, so on and so forth.
April 11, 2009 at 3:36 am
i take your point, the point of investing in a SAN though is you can lose a switch or a disk and the array is still available. The OP states he has an old Hitachi SAN, I wouldnt advise to use that over the newly purchased equipment.
What do you think mamangement would say when they find out you're not making full use of the very expensive equipment they signed off?? As a manager i would be pissed if this happened to me
In my view decommission the old SAN or farm it out to DR let the new SAN do its job.
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