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Can the Dell Equallogic 6100/4100 replicate databases like mysql, MS SQL 2012, and Oracle 11g?

I would like to set up my web applications and their databases in VMWare 5. They would run off the equallogic and be synchronized with another equallogic at another site.

Or is it best practice (and safer) to use other means to replicate the databases?

My plan is to be able to load balance (and perform DR) between 2 sites each with their own equallogics that have their own up-to-date copy of each of the databases.

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They can help with replication but they need DB quiecing support, otherwise you'll inherently get data corruption. In my experience it's always far better to get the DB engine itself to do the work - they're designed to do just that.

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    Agreed. Application level replication is probably the correct way to achieve this. – joeqwerty Sep 13 '13 at 19:38
  • Ok. Thanks for the quick response. Aren't VMs replicated in VMWare with quiescing? – James Sep 13 '13 at 19:58
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    James - You're talking about 3 different things: 1. Storage level replication. 2. VM level replication. 3. Application (database) level replication. Which one are you interested in? – joeqwerty Sep 13 '13 at 20:08
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    @James VMware can quiesce the filesystem, but the databases are a wholly different matter. – Sammitch Sep 13 '13 at 20:10
  • @James - Only Windows can be co-quieced via the combination of VMTools and VSS - theoretically you could force VSS to quiece MSSQL but there's a good chance the snap would fail during the wait time. – Chopper3 Sep 13 '13 at 20:27
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Yes, this can be done on SQL databases in conjunction with the Equallogic Host Integration Tools.

For database-consistent replicas that are handled directly by the Equallogic storage, you need to give your SQL VM direct iSCSI access to the SAN, and your database needs to be stored directly on an Equallogic volume (not on a VMDK within a datastore within a volume). You would also need to install the Host Integration Tools on the VM's OS to allow that system to communicate with the array properly, so that a snapshot can be created just after data is quiesced.

For Oracle 11g databases, I don't believe the Host Integration Tools are compatible just yet. You may consider referencing the Equallogic whitepaper that references "Backup & Recovery using RMAN and Snapshots" for more information on a good solution there.

I'm not actually familiar with mySQL, and can't provide much insight for support there.

Your plan for DR AND load balancing doesn't work out well with this setup though, as Equallogic replication is asynchronous and doesn't give you an "always live" copy of the data at the DR site. You would need application-level replication to accomplish that goal, similar to the functionality provided in Microsoft Exchange (I believe the feature is called a "consistency group"?) - I'm sure something like this exists within MS SQL, though I don't know how it compares to EQL replication.

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If you are using only myisam tables then "flush tables with read lock" will commit all changes to disk and close the files. You can then take a snapshot of the file system. Release the lock with "unlock tables". This does not work with innodb tables in Mysql 5.1 and earlier. I don't know about newer versions.

I am not aware of an integrated solution for equilogic so you will have to script this yourself.

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