Malcolm, As you may be aware, we have used Doubletake her now for about 2 years give or take. The concept of the software is twofold: 1. To provide real time mirroring between two machines 2. To give a failover situation where the mirrored server immediately takes over from the failed primary server and assumes not only its role but also its IP address whilst the failed primary server is repaired.
It accomplishes these tasks superbly and we actually do a live failover once a month as part of our month end procedure with a failback after 24 hours so as to test that it really does work. In addition to our primary and secondary server we have a tertiary server that is solely there to take snapshot backups off the secondary realtime server once every hour - again using Doubletake. These snapshots are logged on the tertiary server hard disk as well as tape. So, worst scenario is that primary server goes down, secondary server kicks in within 30 seconds. Then secondary server fails - God Forbid. We can fire the last hourly backup snapshot up onto the tertiary server in about 45 minutes and still be up and running. Our kit (all servers) are all HP with raid 5 I think that Doubletake would do your job as long as you have the primary and secondary servers permanently connected. One thing that Doubletake doesn't like is the mirror to be taken off line at different times as you have to manually control the rebuild when it comes back on line. One thing that I don't like with the product is that the fail back can be handled automatically by Doubletake (this is in fact the default setting) but it seems to get confused when this happens and from an operational point of view it isn't good anyhow. For example in the situation where the Ethernet connection on the primary server is intermittently on or of (we have had this happen) the primary server would dance between the master and the secondary - not recommended. So, I have set it so that once the primary server goes down, it stays down until a manual fail back can be organized. So, in summary, if you want realtime backup with a server and a backup machine which are permanently there then Doubletake is your answer. By the way we run a mixture of Client server (MSSQL and MySQL) and VFP tables/databases on the server and as a matter of course, if the failover does happen I automatically reindex the main VFP datafiles just in case. The Client/Server stuff just works as there are realtime backup agents for them built into Doubletake. Cost of the software is about $1500 I think and it is licensed by machine "pair" i.e. one copy can be used on 2 machines (primary and backup machine) Setting up is initially simple but there are lots of "not obvious" bits in there. However tech support is first class and they have just revamped their help files which has helped. Overall rating - 5 star and the ONLY solution that I could see working that actually worked in the pre sales demo with some of our data (VFP .exe and tables on the server) when the power was pulled on the main box. Everyone else with a solution said it worked but either couldn't handle the VFP tables or just plain lied and tried to sell us promises. Dave Crozier -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Malcolm Greene Sent: 17 January 2008 19:01 To: [email protected] Subject: [NF] Feedback on DoubleTake? Dave, Saw your mention of DoubleTake and was curious to hear your thoughts on this product. I'm looking for a product that will allow me to use a cheap pair of laptops vs. a single high-end RAID server for a portable development environment I'm putting together. Does DoubleTake sound like it would give me a similar level of failover with two networked machines as I would get with a traditional RAID server? I don't need production quality failover - just hoping to minimize down time if a non-RAID server fails. I would be grateful for your time and thoughts on the following: 1. Approximate cost (the Doubletake website doesn't show) 2. License method (CPU, VM image, other) 3. Ease of initial setup and ongoing maintenance 4. Problems/hassles/disappointments 4. Overall recommendation Thanks! Malcolm [excessive quoting removed by server] _______________________________________________ Post Messages to: [email protected] Subscription Maintenance: http://leafe.com/mailman/listinfo/profox OT-free version of this list: http://leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/[EMAIL PROTECTED] ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
