Maybe FreeNAS isn't for me??

[JimPhreak]

I've been looking into using FreeNAS for a new dedicated storage device I'm building for the past few weeks. However I have 8 x 2TB drives (that are I'm using in my current home file server) to go in an 8-bay NAS case and want to use as much of that space as possible in a the VDev(s) I create. However it seems 8 disks is not recommended for a RAIDz2 VDev. I'm also a little concerned that if I also wanted the ability to expand down the line and now after reading that if I wanted to say add another small VDev of 2 disks that if that VDev failed I'd lose all my data in the zpool.

So what are the main advantages for me going with ZFS in FreeNAS over say just sticking with a RAID10 setup that I'm currently using?

 

[survive]

Hi JimPhreak,

I'm not sure anyone is really going to step up and give you the sales pitch to move to zfs. There are plenty of pages that will explain the advantages you get with zfs if you just stuff "advantages of zfs" into google.

If you haven't, read through this: http://forums.freenas.org/threads/slideshow-explaining-vdev-zpool-zil-and-l2arc-for-noobs.7775/

it covers a lot of things you need to know about zfs & how it works.

I wouldn't give up on zfs if the best reason you can come up with is a less-than-mathematically-ideal number of disks. If you put together the type of system you were planning in other threads then maxing out a gig-e port is nearly a certainty.

The "expansion problem " is there....that's just one of the things you have to deal with & plan around with zfs...swapping out the drives for bigger drives is one way to grow a pool somewhat painlessly.

-Will

 

[JimPhreak]

Hi JimPhreak,

I'm not sure anyone is really going to step up and give you the sales pitch to move to zfs. There are plenty of pages that will explain the advantages you get with zfs if you just stuff "advantages of zfs" into google.

If you haven't, read through this: http://forums.freenas.org/threads/slideshow-explaining-vdev-zpool-zil-and-l2arc-for-noobs.7775/

it covers a lot of things you need to know about zfs & how it works.

I wouldn't give up on zfs if the best reason you can come up with is a less-than-mathematically-ideal number of disks. If you put together the type of system you were planning in other threads then maxing out a gig-e port is nearly a certainty.

The "expansion problem " is there....that's just one of the things you have to deal with & plan around with zfs...swapping out the drives for bigger drives is one way to grow a pool somewhat painlessly.

-Will

Yes I've read through the entire slides how and thanks for the reply Will.

If you had 8 disks and an 8 bay hot swappable NAS case what would you do? Just use 6 drives, 2 for spares and leave 2 bays empty:?

 

[cyberjock]

The only thing I'll add over survive's post is that hardware RAID doesn't protect from silent corruption. If you read up on it, its become a bigger problem thanks to hard drives becoming less reliable.

But as survive said, stay or go, the choice and the data is yours to do with as you please.

RAIDZ2 of 8 disks isn't an optimal configuration, but its not exactly a configuration I wouldn't use. If I had a system with 8 disks and it had only 8 disk slots, I'd do a RAIDZ2 of 8 disks. Unless you are aiming for high performance medium-to-large size business use the optimal configurations don't provide an appreciable benefit. Especially for home use. Neither of my pools are "optimal" and I smoke my old RAID arrays with the same disks.

 

[JimPhreak]

The only thing I'll add over survive's post is that hardware RAID doesn't protect from silent corruption. If you read up on it, its become a bigger problem thanks to hard drives becoming less reliable.

But as survive said, stay or go, the choice and the data is yours to do with as you please.

RAIDZ2 of 8 disks isn't an optimal configuration, but its not exactly a configuration I wouldn't use. If I had a system with 8 disks and it had only 8 disk slots, I'd do a RAIDZ2 of 8 disks. Unless you are aiming for high performance medium-to-large size business use the optimal configurations don't provide an appreciable benefit. Especially for home use. Neither of my pools are "optimal" and I smoke my old RAID arrays with the same disks.

Thanks cyber. Could you possibly explain what exactly is the reasoning for these "golden" numbers of disks and what differences one might see running a RAIZz2 with 6 disks compared to with 8?

 

[cyberjock]

It has to do with stripe sizes and parity info. It's kind of long winded, but if you search around I'm sure you can find the answer. Hardforums has a good explanation for the "magical" disk sizes.

 

[cyberjock]

The thing to keep in mind is that ZFS is designed for enterprise class environments. Very big pools, very big systems, and reliability trumps performance. As such, there are things that enterprises would never consider doing(such as adding just 1 disk to a server), so those "limitations" aren't limitations for the target market. Additionally there's no "recovery tools" for ZFS. If your pool gets trashed don't even think about using the standard recovery tools you may have used in the past. They don't work and the cost of recovery of trashed zpools is 5 digits... to start. Mostly this is probably because enterprises keep religious redundant backups so they aren't going to waste their time with data recovery and will recover from their backups. But, if the forums are any sign, most home users don't backup their data.

Essentially, you'll either learn to accept the limitations or go elsewhere. Many are okay with the limitations, but some still don't like them and leave.

 

[survive]

Yes I've read through the entire slides how and thanks for the reply Will.

If you had 8 disks and an 8 bay hot swappable NAS case what would you do? Just use 6 drives, 2 for spares and leave 2 bays empty:?

I have 8 disks and did raidz2 without hesitation. I tested the difference with "dd" (crude, I know) and it cost me 40MB/s.....went from 480MB/s to 440MB/s so the extra redundancy was well worth the cost.

To answer your question more specifically, first thing I would do is not focus on the hot-swap chassis. Hot-swap is nice & they certainly look cooler than a plain old case but honestly, how often do you have to swap a drive? I've replaced 2 drives in 2+ years.

Assuming you don't have a need that would be better filled with a stripe of mirrors or a pair of raidz1's (something with bettter IOPS) I would certainly be comfortable with an 8 drive raidz2.

-Will

 

[JimPhreak]

The reason I went with an 8-bay hotswap case is because I don't have the space for another tower (however small it is) and cube cases can't fit 8 hard drives. It kind of won out by default. I'm in the process of building 2 VM nodes in cube cases that can be stacked on top of each other with my 8-bay NAS stacked on top of that because of my lack of space. Therefore that's what I have and it is what it is.