Hi there guys,

I wanted to ask for your opinion on this.
I want to set up a NAS, and wanted it to have the following...characteristics:
1. Should be as light as possible. But still with some window manager of some kind. It'll actually run on an atom525 with as low as 2gb of RAM, and possibly from a pendrive.
2. Somewhat user-friendly. I'm not a newbie to linux, but still I'm no power user.
3. I'll have to install a number of applications on that, so I can't use anything pre-packaged like freeNAS, openfiler etc.
4. this is the most important part: it'll have to manage disk space in the best way possible (quantity-wise) while still providing redundancy.

I was considering unRAID or possibly BeyondRAID (http://en.wikipedia.org/wiki/Non-standard_RAID_levels) as I wish to mix different sized drives while still using all the space I can (for example: 2x2tb + 2x3tb disks would give me 6tb total; those two will give me 7tb while still saving the last 3tb disk for redundancy)

Now, I was also checking out ZFS, but I don't think it can provide this kind of feature. I also hear it has quite a lot of other drawbacks I won't discuss in detail here.

So, do you know whether there's a simil-raid level/feature/filesystem/whatever that can provide all the features I need?
Drobo enclosures are awfully expensive (and besides, I already have the metal) and UnRAID also provides the OS, which I don't really want. I'd rather have a module to include in the kernel I choose, in the distro I choose.

So, what's your take?

You could also use mdraid create a raid 5 with the 2 2TB disks and 2 2TB partitions on the 3TB disks that will use 2TB for redundancy and create a raid 1 with the remaining space on the 2 3TB disks that will take also 1TB for redundancy. I would not install a wm. But setup xdmcp so that you can remotely run a wm. With as a benefit you don't need a monitor and keyboard for the nas.

Sadly, 42 is not the answer, this time

hmmm, that's an interesting approach...I wonder how would scalability be, though.
I never worked with software raid in linux, before...how would things go if I decided to add more disks, in the future, or otherwise modify the geometry of the array(s)?

The remote wm seems interesting. I planned to install some kind of web interface for casual management, but I thought I'd still need a wm + vnc for more dedicated operations.
Where could I find more information about that?

Thanks for the reply anyway.

A mdraid 5 you can grow by adding a new disk. A mdraid 1 you can't grow, but because the data is on 2 disk you can remove one disk from the raid array replace it with a larger disk or Partition create a raid 1 on this new disk with a disk missing, then copy the data and replace the second disk or partition and add this to the array.
If you are behind a router you can use plain xdmcp. If you want to connect to your nas over the internet you have to use xdmcp over ssh. Because xdmcp is not encrypted.
How to setup xdmcp http://tldp.org/HOWTO/XDMCP-HOWTO/index.html

Remember raid is no backup solution
If you got valuable data photo's and others make a backup of it for when lightning strikes or your nas burns down.

Tips what you can do with mdraid http://wiki.linuxservertech.com/faq/...=11&artlang=en

BY “3. I'll have to install a number of applications on that” you mean the machine should offer additional services besides NAS?

Wow, too much information!!!

thanks a lot, whizje, I'll have to have a look into that.
but what would be the main advantage in using xdmpc over using a regular windows manager and vnc?
I mean, I'm sure low on resources, but something like enlightenment doesn't seem heavy at all.

Reuti, yes.
Actually I'm trying to setup a double solution on the same common ground. One would be a basic nas for the (very small) company of a friend, where a couple of agents should basically dump invoices and such, nothing fancy, though I suppose she'll want to run some other application there too, no idea what for the moment.
Then, I was researching stuff for my personal home nas (to feed my mediacenter) and thought...why not base it on the same design?
I'll be running some few more applications like a media manager, jdownloader, TheRenamer...stuff like this.

Of course redundancy/backup is much more important in her case, I'll probably have her subscribe a service like crashplan or something similar, I'll have to look into it.
For me it's very basic: I'd like to set up a very flexible raid solution so that I can just be somewhat protected. Then, if I lose a couple terabytes of tv-shows, well...I'll probably have most of them on dvd/bluray already, and the rest I can re-download. No great loss.

Anyhow, thanks to both of you for the insight.
If you have anything more to add, I'd love to hear it

Vnc is much slower. But vnc is also a little easier to setup, but uses more recources.

Other tips use a ups (Uninterruptible power supply) and as filesystem I would advice stick with ext4 without any fiddling it's a high performance filesystem.