Getting my head around all the different options

[alexktz]

Hi there,

I'm going to be putting together a FreeNAS box over the next few weeks to accomplish several tasks, the main job is to be a media server box. It needs to run various servers (most of these appear to be FreeBSD compatible, please correct me if I'm wrong). Sabnzbd, Sickbeard, CouchPotato, Air Video Server (for remote iOS video streaming) and an SQL server to sync up XBMC libraries between multiple jail broken Apple TVs (I don't know how to achieve this yet!).

The main crux of my question is this, based on my hard drives (will list below and don't want to buy new ones right now thanks to Thailand I'll be waiting till 2tb is sub £70 again) what options do I have regarding maximum storage space vs full redundancy?

I understand RAID5 requires matching drives, so that is probably out of the question. I've read many posts regarding raidz and that looks promising. My ideal world consists of a raid5 style % loss of space vs redundancy with the ability to be able to add drives over time to the array without having to destroy the array and start from scratch. watching an old episode of systm (pre runner to tekzilla) they mentioned unraid which uses the largest drive for parity data on the rest. Looks ok but what other options does ZFS and raidz give me. Pros vs cons.

Currently I own 2x 1tb, 1x 1.5tb and one 500gb drive. New drives will be added eventually - I just can't bring myself to pay 3x prices from last year. It hurts. i haven't yet purchased the mobo or CPU yet so suggestions welcomed (bear in mind it will be doing some transcoding some i3 is currently in my mind).

To recap, I want a raid5 style system using around 33% of the available space for parity but that I can add to whenever and without data loss.

 

[survive]

Hi alexktz,

I don't think FreeNAS will suit your needs then. You might want to look at something like a Drobo if you want to be able to mix & match drives. ZFS will use the capacity of the smallest drive when you make a pool.

If you can bring yourself to buy another 2TB drive right now you could do raidz (RAID-5ish) on 4 drives (2X 2TB, the 1.5TB & the new 2TB drives) and get about 4TB (4X 1.5TB), then later on swap out the 1.5 TB drive for a 2TB to get at the unused space on the rest (4X 2TB).

-Will

 

[matlock]

on a side note to your drive expansion idea...

(pardon if my lingo isn't up to par- but hopefully you get the idea)
lets say you start with three hard drives and create a zfs raidz pool- when the day comes and you purchase 1 or two more drives, you can't simply 'add' them to your original 3 drive pool. IF you did add a drive to the pool, it would effectively 'ruin' your raidz configuration.

In order to add to your original 3drive raidz pool and keep redundancy, you would need to add another 3drive raidz pool....

I read this in another post somewhere on here, i'll try and find the link and post it. Maybe someone who's more savvy can clarify, or maybe confirm my above comment.

(http://forums.freenas.org/showthrea...-ZFS-with-RAID-5&highlight=adding+drive+pool)

-Matlock

Just food for thought - and again, maybe someone can confirm if what i'm saying here is accurate and would work.
I plan on having 5 matching 1tb drives in my freenas. But I currently don't have them. So what i've done is scrounge up 5 different drives - configured them in a zfs raidz pool, and when the drives arrive, replacing them one by one.

 

[ProtoSD]

on a side note to your drive expansion idea...

(pardon if my lingo isn't up to par- but hopefully you get the idea)
lets say you start with three hard drives and create a zfs raidz pool- when the day comes and you purchase 1 or two more drives, you can't simply 'add' them to your original 3 drive pool. IF you did add a drive to the pool, it would effectively 'ruin' your raidz configuration.

In order to add to your original 3drive raidz pool and keep redundancy, you would need to add another 3drive raidz pool....

I read this in another post somewhere on here, i'll try and find the link and post it. Maybe someone who's more savvy can clarify, or maybe confirm my above comment.

-Matlock

Just food for thought - and again, maybe someone can confirm if what i'm saying here is accurate and would work.
I plan on having 5 matching 1tb drives in my freenas. But I currently don't have them. So what i've done is scrounge up 5 different drives - configured them in a zfs raidz pool, and when the drives arrive, replacing them one by one.

Hi Matlock,

You're right on target and it's nice to finally see someone new like yourself demonstrate they grasp the concept of how ZFS works and improvise with the brilliant idea you suggested.

Yes, you can start with ANY 5 drives in a pool like you suggested and replace them one at a time. The catch is, and think you probably realize this, is that your pool will only be as big as 5x the size of your smallest disk until they're all replaced and a zpool expand is done. If you do a replace on the smallest disk, and then do an expand afterwards, it should expand your pool to the size of your next smallest disk. If all of your disks were the same size to begin with, then you'd only do the expand after replacing all of them.

Thanks for posting a great suggestion that hopefully other noobs will read and understand like you did.