PP Pro suitable for unattended remote backup system?

[IanWorthington]

I'm wondering the Pogoplug Pro would make a good base for a remote backup system.

My preliminary list of should-haves is:

o RAID5(?) to protect against disk failure. Not so good over USB but maybe it would work?
o Journaling fs with auto-snapshoting to allow for 1) auto recovery after failure, 2) infinite backup history
o Support for rsyncrypto (or similar) to allow rsync updates but maintain files encrypted without the ability to decode them in the event of hardware theft.
o Some way to shut the unit down cleanly in the event of imminent power loss (as advised by a ups).
o Some way to start the unit on resumption of power
o Some way to force a restart of the unit in the event of a lockup

Has anyone already done any work on this/have any thoughts on this? Is the PP pro the best hw platform?

i

[WarheadsSE]

The raid 5 would be best implemented outside of the plug, as an enclosure.

There is no power button. Unplug, replug. (or mod a serial cable and connect to the root console device.)

I suppose rsyncrypto would be usable..

Encrypted drives take horsepower you might not get out of the plug.

[kmihelich]

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.

[IanWorthington]

Thanks for your comments.

Totally agree that raid in an enclosure would be a better idea, but given that 1) ultimately it's connected via usb anyway and 2) it would be cheaper to deploy standard PC hardware, I'm tempted to explore first if raid over usb is feasible.

The bandwidth to the device will be limited by the upstream speed at the other other end, say 50 kB/s. I don't want to use whole disk crypto for other reasons: namely that it would require the crypto credentials to be held on the backup device, making it decryption in the event of theft. rsyncrypto appears to remove that problem as the file is transmitted in encrypted form, at the (possible, maybe even probable) expense of reduction in security. I'm not talking here about wanting to prevent access by the NSA though, just by some bod that steals the equipment from the remote site.

ZFS looks useful, thanks for the pointer. 2.6.36 is above the kernel version used on centos 5, the distro I'm most familiar with, though I don't yet know how one goes about loading these on a consoleless pogo. Or am I stuck with what ever linux is shipped with it?

Any pointers to sources for serial watchdog cards? How might those interface to the pogo?

Is the pogo in fact a good platform for this, it is it just too limited? Would I be better off with maybe a Revo?

i