Not sure if you’ll see this but check out Greyhole: http://code.google.com/p/greyhole/

It’s in a relatively early stage of development but mimics what WHS did with its drive extender feature.

I still wouldn’t use it for my parents, as they want a single removable backup drive, and this would turn it into a bit of a mess. There also isn’t an Ubuntu package for it yet.

Hi Steven, apologies if I miss a question or two that was quite a comment!

Basically LTS vs the latest comes down to how “hands on” you’ll be – if you want to set, forget and keep it in service for several years it would probably be more prudent to use the LTS release. Otherwise the latest generally offers worthwhile improvements, and is what I’d use myself. Having said that however, I’ve only used Maverick on my laptop and a couple of test servers thus far, so I don’t know what improvements it has that are relevant to a media PC.

You can absolutely read the dives in another box, and even reassemble the raid because mdadm stores the geometry in a superblock. Basically all you would need to do is plug in all the drives, boot off a box with mdadm install (not sure if it’s on the live cd) and “mdadm –assemble –scan”. The only reason I used NTFS for the backup is to make it easier for my parents to read in the event of disaster (especially since I’m over the other side of the world). Any Linux live CD will read an ext3 or 4 volume.

Actually I haven’t done a partimg of the OS drive, even though that was part of the original intent. After running through the process I really didn’t see the point. My parents wouldn’t be able to do the reimaging any way and in 6 months there’s a new version which I’d rather use, so instead I’d rather document the process and make copies of any config files I alter. That way it’s easy to do again from scratch with a new version.

Performance of eSATA is excellent – it’s exactly the same as an internal SATA drive. But since the backups are incremental snapshots, USB2 is plenty fast enough as well.

CF over IDE is not especially fast, and not what I’d call slow either, but it does depend on the quality of the CF card you use. I actually ended up reverting to a SATA disk for this particular media PC, due to issues with the adaptors. I tried two different ones (both admittedly very cheap), and kept getting write errors. One of the newer SATA ones would probably be better. I did some googling on the issue of write wearing, and from what I read it would seem CF has some measures to reduce write wear, so I wasn’t too concerned about it. You could make the swap file small or put it on the raid array if you’re worried.

RAID6 is a good compromise, it just really needed an extra disk for this setup. If you have 8 or so disks it starts to make sense but with a 4 disk array I’d rather use RAID10.

Yes I have tested the array degraded, it works fine. I once had trouble adding a disk back in to the array so I deleted it, erased the partition tables on all the disks and recreated it from scratch only to find the file system still intact after assembly. So it can be pretty resilient and forgiving of mistakes, but if I’d recreated with a different block size or partition offset it would obviously have been hosed.

First, thanks for the thorough and fantastic article!! I’m referencing this quite a bit in my 10.4 home server. For reference, it’s a Dell poweredge 840, upgraded to a Pentium Dual Core, with 4GB RAM, 4x 1TB SATA drives for data, and 1x scsi u160 10krpm 36GB drive for OS. I have a few questions, from the perspective of someone that only occasionally dips his feet into linux:

I’m using 10.4 because of its LTS status. But I’ve read that 10.10 has improved support for cloud storage (and experimental brtfs, but that’s neither here nor there). I plan on using my fileserver for FTP and remote desktop (still torn between VNC & neatx). Do you have any experience or opinion on the use of such a server with cloud storage? Are the improvements in 10.10 not available as stand-alone updates for 10.4, and/or is it worth ditching the LTS operating system for those improvements?

Next, I’ve used ext3 fileshares from windows boxes without a problem. Even after reading about hard vs soft links, I’m not familiar with the practical use those links. Do you know what real-world limits or problems I’d encounter using ext4 for my data drive?

Additionally, I’m not concerned about drive readability in a windows box – if my OS drive or the PC goes, I “should” be able to read the drives from a live CD or new OS install (after re-creating the RAID), even if in another box. right?

Related, do you know if it’s possible to export the RAID configuration settings? I plan on keeping a PARTIMAG image of the OS drive on the data drive and backed up separately. Theoretically, I should be able to re-image a new OS drive and have the RAID properly configured, but I’d like the option of quickly re-configuring the RAID on a new install or while booted via live CD.

How is the performance of the eSATA drive during snapshot back-ups? How’s the performance of CompactFlash over IDE? Are you concerned about rewrite limits using the flash memory as the OS drive?

I feel like RAID6 is a good compromise between space and redundancy. Have you tested with other RAID configurations?

Finally, have you tested restoring a degraded RAID in your server’s configuration?

Thanks again,
Steven

In short, nope :(

The WHS solution is brilliant for that situation, as adding a drive to this setup requires both expanding the RAID and ensuring the backup volume has enough capacity (you could possibly have to add two). I’m not aware of anything that mimic this aspect of WHS on Linux, but Btrfs might be good enough once it’s stable.

WHS asks you to choose which folders you make redundant. The way I look at it, if it’s on the RAID volume it’s important, and if it’s not important enough to duplicate it can be stored elsewhere (on a non-RAID volume).

If you want to easily add drives though, RAID is a bad idea – a Unison’d set of individual hard drives plus a separate backup volume might meet your needs better?

I think you’re confusing some terminology here, but the setup I did remembers where it’s up to thanks to a handy feature of XBMC – if you play a video that you stopped previously it will ask whether you want to resume or play from the start. It does this whether the video is on the local HDD or an SMB share. Obviously it will not resume if you then start playback from another client – the SMB server has no idea where you’re up to, nor is there any way for the new client to know.

What you probably want is something centrally controlled like MythTV, in which case I’d recommend Mythbuntu rather than what I have done here. XBMC is currently a one-machine solution.

I was reading some talk of a shared SQL database in the XBMC forums which may do something similar. In the very least it synchronised the media library and playback stats between multiple XBMC machines, but last I checked it required recompiling the code with some patches and was really only accessible to developers. Hopefully the feature makes it into a future release, but it’s the kind of feature that can impact a lot of the codebase so you’re probably better off using something built with it in mind – like MythTV.

Hi Jesse, you’d be right I haven’t finished writing them. I was setting up the home server for my parents and unfortunately got busy planning a trip overseas. Can’t make any promises on when they’ll be finished, and it’s unlikely to be before 10.10. In the meantime there are other guides to setting up monitoring for mdadm, and the XBMC wiki is pretty good. Hope you can get it setup nicely.

does this mean u havent written thme yet?
cheers
jesse