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SAN snapshot backups

Hi,

I'm a product manager at Red Gate, on the SQL Server DBA tools side of the shop. In the last few weeks, I've come across a couple of people who are using entry-level SANs for their SQL Servers, and want to take advantage of SAN snapshot backups.

Now, it's one thing to do this for ‘normal’ file data... but when you start to take snapshot backups of database files, you're in a whole other ball game: unless you ‘quiesce’ the database, you've got a significant risk of ending up with a useless backup.

From the research I've done, it seems that some SAN vendors sell utilities that will quiesce a database prior to taking a snapshot, and wake it up afterwards. But clearly not all of them do, and it seems it’s the entry-level SANs that are missing such utilities.

Sounds like a gap in the market? BUT… to be able to automate a "quiesce -> snapshot backup -> wake up" process, there will need to be a programmatic way to trigger a SAN snapshot backup

So, here are my questions:
1) which SANs come with such a utility, and is the utility affordable?
2) which SANs don’t come with such a utility, and do they have an API to trigger a snapshot backup?

Please post here.

Thanks,

Colin.

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Replies to This Discussion

Permalink Reply by Matt Simmons on October 12, 2009 at 7:48pm

Hi Colin!

I've got EMC AX4-5s, which is on the low end of the Clariion line. I could use EMC SnapView to programmatically do this, although I don't. I'm sure other vendors provide similar software (and that others will corroborate)

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Permalink Reply by Colin Millerchip on October 12, 2009 at 8:59pm

Hi Matt,

Thanks for the reply. Do you have any idea on the cost of EMC SnapView?

I know that some other vendors do provide such tools, and from the looks of things SnapView will do all three steps of quiesce -> snapshot backup -> wake up. But I know that some low-end SANs don't -- for eg, not all Dell SANs come with such tools, nor with the necessary APIs. Anyway, it'll be interesting to see if others have experiences on this.

Cheers,

Colin.

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Permalink Reply by Matt Simmons on October 12, 2009 at 9:05pm

Well, not being able to find a price on the EMC website, I searched the "back alleys" and found this:
http://www.getprice.com.au/EMC-EMCAX4-21-SNAPVIEW-Gpnc_521--4060034...

$3k roughly, but I don't know how it's licensed, as in by the array, or by the server that it runs on. Probably whichever means you pay more. :-)

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Permalink Reply by Isaac on October 14, 2009 at 8:17pm

I’m foremost a server admin and an IT manager as opposed to being a dedicated storage admin so I don’t have tons of storage experience but I’ve run a few boxes and I’ve architected some SANs as well so take this with a grain of salt.

All the storage arrays I’ve admin’d have had a command line way to handle snapshots and this was always included in the cost of the snapshot license. Software to integrate the array with applications has often been expensive but if you’re in the market for a larger box it’s not a big deal … if you’re buying 40TB of NetApp then you can afford SnapMirror. For smaller shops (my current work for instance) budgets are smaller and you may not be able to throw down the money for a fully integrated solution.
In the past I’ve worked with the storage team where they give me a script to snap the volume and I provide a script to quiesce whatever is using the volume and that’s worked well but it’s a homegrown solution with all the pros and cons that go along with that. The biggest issue was the apps as opposed to the storage, tbh. It was easy to snap a volume on demand but getting a filesystem, a SQL server, Exchange, or random app XYZ to quiesce was always harder, at least for me.

If you’re looking at developing a product I’d be more interested in something can talk to the apps and quiesce them before running an arbitrary user provided script to talk the array. I’d like something that would be integrated out of the box with Exchange, SQL server, VMware, etc … and then I’d only need to deal with providing a script. I’d like it to be scheduled and able to alert me if something goes wrong. If this hypothetical software could, out of the box, talk to some popular storage arrays then that would be great but not absolutely mandatory. There is already software that does that but it’s usually out of reach for small shops for cost reasons.

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Permalink Reply by Colin Millerchip on October 16, 2009 at 11:57pm

Thanks for this Isaac (and to "J. Hord" who's also posted in the last few hours). To a certain extent, this confirms my hypothesis that there's a need for a 3rd party tool that could quiesce SQL Server, for those SAN sysadmins who don't have the budget for the vendor-supplied tools (eg, SnapMirror).

... but putting my commercial hat on, whether it's one that makes any business sense is another question!

I really appreciate your feedback -- many thanks!

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Permalink Reply by J. Hord on October 16, 2009 at 6:48pm

For the most part all of the SAN vendor utilities, on the windows side of things anyhow, use an API call to the Microsoft VSS subsystem to freeze/thaw the resources needed for the snapshot. This seems to be true for both MSSQL and Exchange regardless of weather the call is to a SAN for the snapshot or a backup software package. At one point we attempted to 'outsource' a project to make this call for us to a MS 'Gold' partner since our SAN vendor didn't have the capability and they were unable to accomplish the task. I'm not sure if the failing was on their side or if MS is just loathe to share the needed info/specs with any except a select few major vendors.