UNIX Data Replication

[Andrew Pollard]

Hi,

I am looking for an inexpensive way to replicate mission critical data to a DR server 100's of kilometers away.

The budget to purchase something can not exceed $20,000, which rules out VVR and SRDF and we have already tested "rsync".

Can anyone suggest any other product? Does Openview Storage Media work on replicating UNIX data?

The servers are both RP8400 and both are connected to DMX frames.

Thanks in advance

Andrew

[A. Clay Stephenson]

The fundamental problem is that the cost of the hardware (even very expensive hardware) is going to be swamped by the network costs in just a few weeks or months. The costs of high-bandwidth networks over time will exceed everything else.

Rsync is smart about sending only changed portions of files so it is quite smart and saves bandwidth. If you have already written off rsync then essentially no other software solution is going to be significantly better.

You aren't going to like my idea but you have already narrowed the parameters to essentially one answer: FedEx Overnite with a box of tape(s).

[Steven E. Protter]

Shalom,

If you are willing to pay for the bandwidth rsync via ssh will work just fine.

You budget is probably to small.

Mirror/ux does not work through low band witch connection.

If your data is Oracle Oracle Dataguard can replicate the oracle database nicely.

SEP

[Gerardo Mora]

The budget to implement a mission critical data replication you have is too small, but if you are using Oracle (at least Oracle 8i)you can implement "Oracle standby database" solution, I guest this is one of the shippest options for data replication. If you are interested, check Oracle Metalink note: 74185.1

[David DiBiase]

I can vouch for Oracle dataguard. We use it on 10gR2 with a failover machine. It was a bit of a pain to get it set up the first time but, once done - very smooth.

Dave

[A. Clay Stephenson]

Before we go too far down the Oracle road, note that Oracle was never mentioned. This may be Oracle related but there are no data to support that. Given that rsync was mentioned in the original posting, I'll continue to assume that this is a general data replication problem.

[TwoProc]

You say you've tried rsync, what's the problem with that approch? Maybe we can offer suggestions as to making that work. You didn't offer how much data you were moving, but you must realilze that the answer would largely depend on the size.

[Andrew Pollard]

Hi,

We are not using Oracle and the Database we do use (Progress) has it's own replicator tool.

We would just be replicating data.

We have not found anything wrong with "rsync". It seems to do everything we want and it seems pretty easy to use. Our management on the other hand is not convinced because "rsync" is free and they are worried we would not get quick and reliable support if something went wrong. That is why we are looking for a "cheap" alternative.

Thanks for all your suggestions so far.

Andrew

[A. Clay Stephenson]

Well, in that case, you could choose to use rdist -- which is supplied with HP-UX but can only work at the entire file level so your bandwidth requirements will be quite high.

One of the things that you have not made clear is latency. Are you willing to tremendously throttle down the primary site until confirmation is received that the secondary site has updated the data? Do you snapshot the primary system and then do your rsync (or rdist) against that snapshot so that data that are a few hours old is close enough --- as long as the snapshotted data are a self-consistent data set.

If rsync is a good technical solution for you (and note that rsync has been around a very long time and it is supported by samba.org) then my approach would be to devise a rigorous test plan --- rsync then either works or it doesn't. Each time rsync is updated or patched, you put it through this same test plan. Each time the OS is patched, ditto. Hopefully, you have sandboxes to test on. I would spend the $20K on sandboxes if you don't already have them. $20K will buy quite a bit of equipment on the used market. In any event, even if I bought commercial software to do exactly this same task, I would still have a test plan and put it through exactly the same procedure because the one question I never want to answer as anything but "yes" is "Will my DR Plan work?".