Hybrid Hard Drives

[IanF]

I tried the Ubuntu server option but didn't have a spare DVD drive when I set it up eventually tried unraid and it worked so easily for me.
Still waiting for the disks

[SilverNodashi]

You can definitely use ZFS with 1, 2 or 3 drives but see more benefits with 4 drives+
With ZFS you need 1GB RAM per TB storage.
You can use a small ZIL log drive which acts as parity and it can even be on USB 3

[irneb]

You can definitely use ZFS with 1, 2 or 3 drives but see more benefits with 4 drives+
With ZFS you need 1GB RAM per TB storage.
You can use a small ZIL log drive which acts as parity and it can even be on USB 3

+1 ... what I meant to say is that ZFS would only help Ian if he had 4 or more drives (over what he already has with UnRaid).

The 1GB/TB rule is good yes, but the absolute minimum RAM is 4GB, and recommended 8GB. This is due to ZFS's in-ram caching and logging. And if you turn on ZFS's de-duplication (i.e. never saves duplicate blocks of data more than once even between different files) it gets even worse since this is calculated in RAM also. But the main issue is that you absolutely MUST use ECC compliant RAM chips, so the off-the-shelf stuff is not good enough (gets worse with higher altitudes due to more sun-radiation causing bit-flips in RAM). http://hardforum.com/showthread.php?t=1689724

I've tested this for about a year on a normal PC which I converted to a server, and I've found this to be excellent advice. Has 16GB of "normal" RAM and found at least one corrupt file per week - only way to fix was to copy from backup, ZFS's scrub didn't help at all, it didn't even "know" that the file got corrupt. 1st 2 months on Linux with the ZfsOnLinux separate install, then using FreeBSD instead - thinking that was why the corruptions happened. But no, even with FreeBSD and the native ZFS driver I still got the same corruptions. So it was definitely the non-ECC ram with ZFS's sensitivity to RAM bit-flips. I've had the Ext4 + AuFS system since last year November on the same exact PC, and have yet to find any file corruptions - this file system is less affected by RAM problems.

[irneb]

But the main issue is that you absolutely MUST use ECC compliant RAM chips

Here's an example of what I mean:
4GB DDR3-1600 RAM from the same supplier & manufacturer. Commercial R600, ECC Server edition R850.
Normal desktop RAM (4GB / 8GB)
http://www.comx-computers.co.za/JM16...uy-p-65967.php
http://www.comx-computers.co.za/JM16...uy-p-86804.php

ECC Ram meant for servers:
http://www.comx-computers.co.za/TS51...uy-p-87527.php
http://www.comx-computers.co.za/TS1G...uy-p-66890.php

See the price jump? So instead of me spending around R2100 for a 16GB machine's RAM, I'd have spent closer to R3700. And that, just because I'm using ZFS instead of nearly any other FS.

[SilverNodashi]

+1 ... what I meant to say is that ZFS would only help Ian if he had 4 or more drives (over what he already has with UnRaid).

The 1GB/TB rule is good yes, but the absolute minimum RAM is 4GB, and recommended 8GB. This is due to ZFS's in-ram caching and logging. And if you turn on ZFS's de-duplication (i.e. never saves duplicate blocks of data more than once even between different files) it gets even worse since this is calculated in RAM also. But the main issue is that you absolutely MUST use ECC compliant RAM chips, so the off-the-shelf stuff is not good enough (gets worse with higher altitudes due to more sun-radiation causing bit-flips in RAM). http://hardforum.com/showthread.php?t=1689724

I've tested this for about a year on a normal PC which I converted to a server, and I've found this to be excellent advice. Has 16GB of "normal" RAM and found at least one corrupt file per week - only way to fix was to copy from backup, ZFS's scrub didn't help at all, it didn't even "know" that the file got corrupt. 1st 2 months on Linux with the ZfsOnLinux separate install, then using FreeBSD instead - thinking that was why the corruptions happened. But no, even with FreeBSD and the native ZFS driver I still got the same corruptions. So it was definitely the non-ECC ram with ZFS's sensitivity to RAM bit-flips. I've had the Ext4 + AuFS system since last year November on the same exact PC, and have yet to find any file corruptions - this file system is less affected by RAM problems.

Interestingly, I havn't picked up this behavoiur. My home server runs FreeNAS, on a normal desktop PC with 8 HDD's in, Normal DDR3 RAM and yet I haven't picked up anything like that. It's filled with photos, music, videos and saved data from both my wife and my own laptops and tablet. Our production servers all run ECC RAM so I can't vouch for them though.

But, as far as I know, you don't absolutely ^need^ ECC RAM for ZFS, same as you don't absolutely need a ZIL drive or cache drive, but it's definitely recommended for optimal performance.

[irneb]

It's filled with photos, music, videos and saved data from both my wife and my own laptops and tablet.

That's why. The issue usually only arises when saving files. You're probably not saving and resaving and editing and resaving, etc. etc. etc. those JPGs/MP3s/AVIs are you? I'm with you on using FreeNas for such media server - easiest thing in the world, and the ZFS is awesome (especially with this type of data). I've used it as such also, and loved it - used FreeNas exactly for the same purpose. Went so far as doing the same for my "working file server" too, though installed FreeBSD instead (i.e. the full OS unlike the minimalist FreeNAS) - which is when I started noticing the problem. And then started doing research on how to fix it - only solution: ECC RAM.

It's just when you want to use ZFS in a production server were writes are going to happen on a near per-second basis, you should very seriously consider ECC RAM, otherwise it's not a huge problem since the corruption only occurs very rarely. Yes, not a "necessity" ... same as working breaks aren't "necessary" to be able to drive your car.

[IanF]

OK I got the drives, now just to find a quiet few hours to clone and install the new drives. Probably over the weekend would be best.

[SilverNodashi]

That's why. The issue usually only arises when saving files. You're probably not saving and resaving and editing and resaving, etc. etc. etc. those JPGs/MP3s/AVIs are you? I'm with you on using FreeNas for such media server - easiest thing in the world, and the ZFS is awesome (especially with this type of data). I've used it as such also, and loved it - used FreeNas exactly for the same purpose. Went so far as doing the same for my "working file server" too, though installed FreeBSD instead (i.e. the full OS unlike the minimalist FreeNAS) - which is when I started noticing the problem. And then started doing research on how to fix it - only solution: ECC RAM.

It's just when you want to use ZFS in a production server were writes are going to happen on a near per-second basis, you should very seriously consider ECC RAM, otherwise it's not a huge problem since the corruption only occurs very rarely. Yes, not a "necessity" ... same as working breaks aren't "necessary" to be able to drive your car.

We take a fare amount of personal photos and videos and save to the drive on a daily basis. My wife also does some professional photography and save / edit / save client's stuff on their on a regular basis.
Sure, it's not the same a production server, but it's similar to a small office file server.

[irneb]

OK I got the drives, now just to find a quiet few hours to clone and install the new drives. Probably over the weekend would be best.

Great, let us know how it goes. Which brand did you get? Seagate / WD / other?

Sorry for the off-topic about file systems though.

We take a fare amount of personal photos and videos and save to the drive on a daily basis. My wife also does some professional photography and save / edit / save client's stuff on their on a regular basis.
Sure, it's not the same a production server, but it's similar to a small office file server.

Then I don't know - I probably then just have some bad commercial RAM. Or a bad spot where the server sits. Or bad power. It is on 24/7 though - so that might also be a factor.

[IanF]

I got Seagate desktop SSHD 1 TB drives.
Don't worry about the off topic file systems that is how we learn.