Set up question for multiple 250Gb Hdd's

[burt123]

Hello,

My 1st post here.

I am wondering what would be the best way to setup 16 x 250Gb drives, to get maximum capacity, with some redundancy.

Create 2 or 4 disk vdev's, then add them to a same named pool, or ALL 16 as once BIG pool, vdev ?

Any suggestions will be welcome.

Cheers

 

[Kimba]

Welcome,

I would do Two 8 drive pools in RaidZ2. That way you get 1.5 TB per pool and you can lose 2 drives and still function. Since the drives are probably older they will be more prone to fail.

The problem is always what you are storing and the value of what you are storing. If it is important then more redundancy is better. Even if it is not important you don't want to waist time rebuilding a giant pool when 1 drive fails so redundancy has value on stuff you don't care about as well.

A pool larger than 10 (or 12) disks has too many for ZFS so I would simply make it just 8 disks.

 

[burt123]

Hi Kimba,

Thanks for the reply, I have been trying all sorts of different configurations, and haven't had too much success, yet, but one thing I'm not too happy about it the file transfer speeds over a gigabit lan, from a Windows pc, it's a bit slow, and that's using RaidZ, they tell me RaidZ2 is slower.

I even tried the 8.2 B3 version, liked the changes on the browser gui, but there were a few things that didn't work, eg:- reboot & shutdown.

So just to clarify your suggestion, create 2 SEPARATE 8 disk pools (don't then merge them under the same name)..correct ???

I have actually given up on the 250Gb box for the moment, working on multi 400Gb disk box, will have 8, all up....do you suggest RaidZ2 on that as well...don't want to lose too much storage space.

Cheers

 

[Kimba]

The rule of thumb is if it is an odd number of drives than use a RaidZ1 and if it is an even then use RaidZ2. This is due to performance and space optimization reasons. You should be getting around 40-80 MBS up and down.

 

[burt123]

Kimba,

OK, I had already sort of found out that odd's should be RaidZ & even's RaidZ2, so will give both a try and see how I go.

So I was trying another box, with 4 x 400Gb IDE drives, on a RaidZ, and when copying files from my Windows box, using Teracopy, the speed wasn't very good, I changed a cache setting in Teracopy, and it made a huge difference, but then it would "stall", then start again, etc, etc, and when it finished the transfer, it would "wait" for quite some time, before proceeding with the next file. Don't really know what's going on, but it's a little disappointing :(

Furthermore, I have set up the 250Gb system as you suggested, and I did indeed get 1.5Tb for a pool of 8, using RaidZ2, however, I had a bit of a problem with the data cables on the HDD's, and I had to set up the pools again, but this time I only got 1.3Tb...any ideas why this would happen ??