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When it comes to replicating a LUN or partition to a physically separate server, Linux has DRBD (now in the kernel!). As I understand it, it has both synchronous and asynchronous replication modes. When you have a fast network between your two servers, it can rock hard.

I need to do the same thing for Windows servers. I know there are non-free packages that do this (recommendations would be nice), but considering what we call a 'budget' around here, I need to know more about the more free options. If any.

We're on Server 2008 for the large majority of our storage servers. If R2 will get us what we need, I need to know now so I can schedule the upgrades in 4 weeks.

The crux of the problem is that I need to replicate a bunch of LUNs stored on an HP EVA 6100 (10K RPM disks) and EVA 4400 (mostly the, er, 1TB FATA drives) devices to something else. Now HP has the very nice Replication Manager that'll handle replicating between the two, but we're trying to wean ourselves off of the soon-to-be-end-of-lifed 6100. We need to replicate to something that isn't an EVA.

According to my performance monitoring, the largest part of our storage to be replicated is accessed in a very bursty way (it's file-server data). Backup I/O dwarfs regular I/O by a factor of three. The total amount to be replicated is around 7TB, with a daily file net-change on the order of 500GB (all those Outlook PST files add up). I don't know what the block-level net-change is.

We have Fibre Channel available, and in one datacenter we even have the beginnings of an iSCSI isolated network. But between our two datacenters we are (currently) limited to a single 1 GigE pipe, that will be upgraded to a 10 GigE pipe within the next 12 months.

There are some off-the-shelf utilities out there, I just don't know much about them

Double-Take Availability Seems to do something like block-level replication, but not quite. Could be what I'm looking for.

Veritas Storage Foundation Seems like serious overkill for this particular problem, but would add a lot of flexibility to our environment.

CommVault Simpana Heterogeneous replication, WAN friendly.

And many, many more.

If this environment were Linux with Samba, DRBD would be a near perfect fit. I just don't know if there is an equivalent on the Microsoft side of the house.

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  • Literally no idea how to do this but it's an interesting question - my first thought was to RAID 1 the LUNs but that's stupid ;)
    – Chopper3
    Jul 29, 2010 at 15:39
  • And that file-server is actually a fail-over cluster, so Dynamic Disks are out of the question anyway. That was my first thought too :P.
    – sysadmin1138 ♦
    Jul 29, 2010 at 15:56
  • Veritas Storage Foundation is the only product i've ever heard other people using for these kind of scenarious (disaster remote site replication). Very interesting question, will follow this one closely to see what you end up with.
    – pauska
    Jul 29, 2010 at 21:24
  • @Chopper3: Same thought here initially, too.
    – Evan Anderson
    Jul 29, 2010 at 21:57
  • Erik, we use VSF all over but I'm not sure it would add that much over and above the out of box Windows tools.
    – Chopper3
    Jul 29, 2010 at 21:58

5 Answers 5

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Replication via the storage platform is pretty much always going to be the best bet. Granted the desire to move from one platform to another makes it a lot harder to do as most of the time you can only replicate from one array to another. Now if you are sticking with HP arrays they should be able to replicate between each other so the replication software cost wouldn't be a waste.

Check with your sales person, maybe they can get you a good deal on the replication software if you are in the process of replacing your arrays.

Use your VAR as a resource, that's what they are there for.

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  • We intend to. We're attempting to come up with options beyond just EVA Continuous Access. It'll do what we need, but the last time we checked the price on that it was cringe-worthy. Time to check again, though.
    – sysadmin1138 ♦
    Jul 29, 2010 at 21:46
  • We use it on all our EVAs, if you time it right you can get some silly discounts on HP storage (as in >80% discount!)
    – Chopper3
    Jul 29, 2010 at 21:59
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Take a look at products supporting Open System SnapVault.

Tom

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SteelEye DataKeeper does block level replication of volumes and has work very well for us in similar circumstances.

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besides the mentioned ones, there is also NeverFail and WanSyncHA

I have tried both for mirroring an exchange 2003 over WAN, and they failover nicely. The prices are pretty high though.

Links:
http://www.neverfailgroup.com/
http://arcserve.com/us/highavailability.aspx

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If it was just file servers you needed I would throw in a vote for DFSR, as it's block-level, controllable, free(included) and mesh-like it it's replication, but with at least one no-go limitation: (PST's tipped it off to me) Files must be marked closed in order to kick off a replication of the blocks. If people keep Outlook open, like they always do, 24/7... those PST's will never get replicated in DFSR. Just another reason to hammer the Exchange admins to block PST creation (or block it on your file servers). Also a note to check for any solutions you review is open-file sync support to make sure you don't find out the hard way like we did that open files weren't getting replicated.

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