SAN replication - does SQL service need to be shut down before copying?

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SAN replication - does SQL service need to be shut down before copying?

sqld-_-ba

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December 21, 2017 at 9:25 am

#409885

We're moving to another datacenter. The plan is to replicate all data using SAN replication (HP 3PAR) to the new DC, physically move the servers, and start them up.
The goal is a one-time move, not synchronous/asynchronous SAN replication for Disaster Recovery, or anything like that. We're also trying to reduce the down-time of applications.
Does the SQL service on the datacenter need to be stopped before the SAN 'copy' takes place ?
Is there chance of data corruption if it's not stopped ? Will kicking off the SAN replication automatically 'quiesce' SQL in-flight transactions, like VMWare which works with the VSS service (we'll see I/O frozen messages in the SQL error log) ?

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Sue_H SSC Guru Points: 90860 More actions · Answer 1

sqld-_-ba - Thursday, December 21, 2017 9:25 AM
We're moving to another datacenter. The plan is to replicate all data using SAN replication (HP 3PAR) to the new DC, physically move the servers, and start them up.
The goal is a one-time move, not synchronous/asynchronous SAN replication for Disaster Recovery, or anything like that. We're also trying to reduce the down-time of applications.
Does the SQL service on the datacenter need to be stopped before the SAN 'copy' takes place ?
Is there chance of data corruption if it's not stopped ? Will kicking off the SAN replication automatically 'quiesce' SQL in-flight transactions, like VMWare which works with the VSS service (we'll see I/O frozen messages in the SQL error log) ?

How it all works depends on the vendor for the SAN. They implement things differently and can have different approaches based on your infrastructure, what you purchased (or are willing to purchase), etc. Best to probably contact whoever you work with from HP.

Sue

Steve Jones - SSC Editor SSC Guru Points: 736478 More actions · Answer 2

If it's a one time thing,I'd shut things down. After all, don't they need to be down for the move? A little more time as insurance isn't bad.

That being said, as Sue mentioned, SAN vendors do have implementations that work great for this without any need to shut down the db.

alen teplitsky SSC-Dedicated Points: 30014 More actions · Answer 3

depending on your workload, i'd look at shutting them down so as not to lose any transactions after the copy

You don't have any spare servers to set up a temporary AlwaysOn cluster?

Arsh SSCertifiable Points: 6354 More actions · Answer 4

If the replication works at bit level , shutting down might not be required. We used a product called DoubleTake which works at bit level and hence didn't require the shut down. For the in-flight queries its best to get a confirmation from the stake holders at SAN management.