Preview of ZFS on FreeNAS 0.7 Server

[proxicate]

Does ZFS only work with raw hardware devices and basically take them over or can it just work with a partial allocation of a drive such as software raid on linux?

[damoos]

@proxicate Zfs can work with files, never mind hardware.

You can create an empty file, and then create a pool out of that file.

If, why would you want to do that ? But you can.. :-)

[proxicate]

@damoos I'd want to do that in order to stagger i/o across various hardware

[thelegendarypaki]

I am curious. I know somebody mentioned this before but I want to know if I can add different size HDDs to the ZFS.I have two 1 TB drives but I am getting a deal on 1.5 TB drive.

[aphor]

ZFS is very nice about heterogenous drives. It won't be able to provide redundancy on 1.5TB if you only have 1TB + 1.5TB, but if you later replace the 1TB drive with a 2TB drive, then you will get 1.5TB redundant storage without having to do any backup or restore.

[damoos]

@thelegendarypaki You can but you only the smallest drives size will be available to the zpool. i.e. 1.5 + 1 = 1

[JamieJWSmith]

Let me get this straight. ZFS allows me to continually add space to my freenas without the need of formatting. I can use raid 5 with zfs so if any hard drive fails, I won't lose my data. Also does zfs need hard drives with the same storage or can they all be different. Thanks for this subscribed :p

[SteveCrothers]

No you CANNOT use Raid 5, Raid 5 would actually destroy ZFS performance and redundancy.

No your harddrives do not need to be the same size, they will pool the storage no matter the size.

I use a 32gb SSD drive to cache my pool at home, and I get about 300% performance increases, and I use a mix of 500's and 1000's for my actual storage. ZFS gets allot of performance from SSD cache drives and lots of ram :) if you got it of course, not a requirement.

[SteveCrothers]

The more I listen to this guy, he mentions allot of raid options you can use. That is 100% incorrect... you don't use traditional raid with ZFS. You use storage pools with multiple parity drives.

[mkleinpaste]

ZFS supports its own version of RAID levels. It supports basic RAID 0,1&10. Then it has its own parity raid as follows:

RAID-Z=min 3 drives with 1 being parity

RAID-Z2=min 4 drives with 2 being parity

RAID-Z3=min 5 drives with 3 being parity

Because of ZFSs commit on write paradigm RAIDZ+ doesnt suffer the write commit whole. It still suffers the RAID5 IO penalty though.

[proxicate]

@mkleinpaste does Raid-Zx have any advantages over raid 0,1 and 10?

[damoos]

@proxicate Look up Raid6

[allanonmage]

What's up with that UI? I downloaded the virtual machine (freenas .69) last night and my web GUI looks completely different than the documentation.

Love the Brittish accent BTW.

[dynamohums]

Very useful overview. Thanks!

[screamingservers]

I think you can put the drives of different sizes in the pool, do not mirror them. I was just reading something about adding a solid state drive or mirror to a pool and the zfs (on solaris) would automatically use the ssd's for small files that are accessed more often (maybe by some internal performance metrics?)

[dre2kse]

hungarianhc, fandibus

The min number of disks required for raidz is 3

If you use HD of diff sizes the space used on them will be that of the smallest disk. So yes you will lose space.

[hungarianhc]

Thanks for that great walkthrough. Question, though - is it possible to create a Raid-Z (for redundancy) with two disks? What would be the benefit of doing that over doing a single mirrored pool? Also, if one of your two disks dies, if you swap in a new one, how do you repair?

[xcarobx9]

@hungarianhc

That would be a mirror vdev then?

If one drive fails (your pool will be "degraded" but still 100%online) you just replace it with a new drive and "resilver".

If your drives are hot-swap the pool will never go offline, if it's not your pool will only be offline during shut-down/replacement.

It will be online during resilvering.

[nlfiedler]

@fandibus: you can, if you manage it well. Chances are there will be some unused space on one of the drives, but even an application like the Drobo can't solve that problem. It just makes it easier to manage. Nonetheless, with careful management you can do it with ZFS and hence FreeNAS.

[fandibus]

Can you use hard drives of different sizes without losing space?