Why is UNRAID cool for home?

I’ve played with many storage technologies at home, ZFS being one of my favs when it comes to performance. But i’ve been looking for something that suits a typical home environment where power usage and capacity is usually more important than performance. Thats where UNRAID has come in…

UNRAID give me these advantages;

  • Different sized disks in a single pool (only requires largest disk as parity)
  • Files are distributed over all the disks – so even if you lost more than a single drive you still still have some of your data. Note : with parity drive you can handle a single drive failing without loosing anything, sorta like RAID4 – non distributed parity.
  • Power usage, since the files are stored on specific disks not all the disks need to power on to give you your file.
  • Runs on a USB stick – no large operating system required.
  • Crashplan module can be installed to provide backup options.


ZFS basics

I’ve had a play with WHS but eventually got annoyed with its lack of performance. Yes i know its not built for performance and typically is used just as a backup / simple store with duplication as redundancy, just i couldn’t stand the speed of the thing. If you were ever unlucky enough (even post power pack 1) to do a copy during the “data moving” the performance was even worse. On a positive note nothing beats it if you have a heap of non-similar sized disks that you want to put together (with redundancy) as a single shared storage pool.

Welcome to ZFS performance bliss….

Grab yourself OpenSolaris (i’m using 2008.11)

The tools of the trade are ;

zpool – this manages the zfs pools

zfs – this manages the zfs file systems

I was lucky enough to have 3 x 250GB drives, which i setup in raidz1 (similar to raid5 – single drive redundancy). The rest of my drives were just setup as a striped volume which contained mainly things i can afford to loose if a drive dies.  I used a separate 500GB disk as the system disk

After i had built the server i put in only the disks i wanted to work with next. So first i installed the 3 x 250GB disks and booted the machine. Running format then Ctrl-C showed me the device names. From deduction you can figure the names of the 3 new drives. Now its time to create a new raidz1 zpool with the following command;

zpool create poolname raidz1 dev2 dev3 dev4

Done – you should now have a mountable (and usable) file system at /poolname. If you didn’t want any redundancy just drop the “raidz1” out of the above command and you would get essentially a striped pool. Check the status of your zpool with this command;

zpool status poolname

Another thing i like to modify at the root of the new zpool is compression. So i usually run this command…

zfs set compresion=on poolname – enables compression (note: this does not typically slow down your file sever if you have the spare CPU). See this post for further details on zfs compression.

To check the settings currently applied to your pool run;

zfs get all poolname

If you wanted to create some additional zfs file systems within he zpool use the following command;

zfs create -o casesensitivity=mixed -o nbmand=on poolname/share

set casesensitivty=mixed  – allows windows to access files (via SMB) if not specified exactly to their original case. (this has to be set on creation). nbmand=on enables Cross-Protocol Locking.

The future of ZFS…

ZFS is adding more and more features as time goes on. I have heard rumors about some kind of de-duplication (single instant storage) type technology being implemented at some point. Also a data merger? – assuming it moves data across the pool more evenly.

Removing a device from a pool is also on the cards. Unsure if this is both striped and redundant pools though?

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