You'd be looking at VMware Fault Tolerance/Lockstep https://www.vmware.com/products/datacenter-virtualization/vsphere/fault-tolerance.html#
Edmund White On Sep 7, 2012, at 3:47 PM, "Edward Ned Harvey (lopser)" <lop...@nedharvey.com<mailto:lop...@nedharvey.com>> wrote: I believe these products exist, but I'm having difficulty finding them. You want to provide HA virtualization... Meaning some VM should appear to always be up, even if half of the underlying hardware were to die. At first blush, it would seem impossible ... Even the fastest network can't possibly keep up with the internal CPU state and memory of the guest VM. But I would swear, some years ago, I saw or heard something intelligent ... The host OS is able to quickly snapshot and diff the guest machine state, so it does this at critical moments, like, when the guest OS is sending outbound network packets. So you don't actually need to keep the complete guest machine state in sync between two machines; you only need to quickly send diffs at critical moments. Then at any given moment, more than one host hardware can be hosting the identical internal system state for some guest VM. >From vmware, the product they call "High Availability" just restarts the >server on other hardware. (As far as I can tell from their tech docs.) Plus, >Vmware doesn't do storage... So you'll have to get your own HA storage >separately. >From virtualbox, you have live migration, but no HA. (As far as I can tell.) If you have a complex service, with apache, database, files, etc... The challenge is, what's the best way to make it HA? You can do some database replication, and use a load balancer, and either NFS or iscsi with mirroring, to make the filesystem HA. But that's a lot of stuff to possibly go wrong. The best I can find so far is to simply mirror the underlying storage of the guest OS, so in a failure, you can quickly easily boot the guest on another host. This is probably ok for a lot of purposes, a brief downtime in the event of failure. But I like to aim high whenever possible... Thanks for any comments/suggestions. _______________________________________________ Tech mailing list Tech@lists.lopsa.org<mailto:Tech@lists.lopsa.org> https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
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