by kmihelich » Sat Jun 11, 2011 4:11 am
I agree with WarheadsSE on all the points. RAID you'll want to attend to externally in an enclosure, though they do get expensive since they're on their own. You could do USB and use software RAID, but that would suffer if you sent a lot of data through it.
To have the plug fault-tolerant, you just need to essentially run the root filesystem read-only. Send syslog external somewhere if you need logs, and make sure the apps you use don't expect to write to the rootfs. This way the plug could lose power and come back up as if nothing happened. Remount-rw to do system updates, all is well.
Crypto will suffer, entire filesystem crypto will be hell. YMMV though, the dual-core in the Pro has been proven to be significantly faster than the other plugs based on the 1.2GHz Marvell Kirkwood. You may surprise us all by having it work decently fast. Running a test scenario would be wise. Rsyncrypto could be the solution you want, if the encryption is done on the sending device, not the plug. I just briefed over their site.
For fs snapshots on Linux, you have pretty limited options. There is the ZFS port, but that is still on-going and afaik doesn't work with kernels above 2.6.36 yet. The only off-hand way I know to do it is LVM+XFS. XFS can't do snapshotting on its own, but in combination with LVM you can do it.
To force a restart in the event of a lockup will require some extra hardware. You'd likely want to set up a serial watchdog card to receive keepalive messages from some app running in the system. If it stops getting those, recycle the power. Whole market of those guys for that express purpose.
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