Thanks guys, some really useful points from all of you. I certainly think a full backup/image of the two systems is definitely required... still not sure about the appropriateness of the dd and dump tools for copying an entire system, or whether another tool such as clonezilla would be more at home.
The 2 systems I'm concerned about are candidates for VMs, and the storage servers would easily reconfigure to a small SAN. Any tips on SAN design?
I dream of a world where our lives can remain private, and our technology can remain open to all.
With Linux, you do not need an "image" - this isn't Windows.
For a "snapshot"/mirror, use rsync.
For real backups, use something like duplicity, rdiff-backup - you know - a real, efficient, backup tool.
Image-based backups for entire systems waste huge amounts of space, unless they know about the file system. With ext4, most of the image-based tools stopped being smart. If you are still on ext2 or ext3, then I **know** partimage understands the file system and will not get all the unallocated space ... but you have to bring the machine down to use those sorts of tools.
Backup tools do not have that limitation. They will backup open files that might be in bad states leading to corruption. I think I said this previously - that DBs are usually the only files at risk of corruption during backups - dump the DB to a text file which can be imported later, then back that up.
If you don't really understand this stuff - start a new thread for server backup techniques to get lots-o-help.
Why use hyper-v for this? KVM or LXC will work better for Linux VMs. Walk away from the proprietary software ... please.
SAN design can be very simple.
* SAN need its own network; never shared (vlans do not help)
* dedicated NICs in every machine for the SAN; dual if you can't have downtime
* dedicated GigE or 10GigE networking
* Fast, enterprise, drives configured in some sort of protected RAID. RAID5 is usually a bad idea for a few reasons.
* ZFS might be a good solution - just be certain you have enough processing power. ZFS provides iSCSI and NFS and CIFS storage. Poor performance can happen, so do your homework.
If you want/need to build your own storage server, check out the blazeback design. They have solved some interop issues.
EMC and NetApp are very expensive, but if you need them, then you need them. Updating a frame can really suck, so if you do go this direction, plan to buy a new frame to replace the old one every 5 or so years. Different HBA device drivers can prevent an entire frame firmware update.
AoE can be a good choice for performance - CoRAID.
iSCSI is more standardized.
I've only designed SANs, I am not hands on at work. Other, smarter people do that stuff - plus the vendors.