Upgrade drives

[Ganzir]

Hello

I am runnin 4 2TB drives in RAID Z1.

I still have 50% free storage, however when this storage starts to run low, how would I proceed if I wanted to upgrade my drives?

Can I simply disconnect one drive an replace it with a larger one, do this to with all 4 drives one after the other and after all 4 drives are changed the volume can be expanded or something like this?

 

[Ericloewe]

Can I simply disconnect one drive an replace it with a larger one, do this to with all 4 drives one after the other and after all 4 drives are changed the volume can be expanded or something like this?

Yes, the pool should automagically expand.

Also, note that you don't strictly need to remove disks to replace them. If you have available connectivity, you can do the replacement in place.

 

[Stux]

Are you aware of the problem with RaidZ1 vdevs which are made out of larger disks?

 

[Ganzir]

No ... what kind of problem?

 

[Robert Trevellyan]

RAIDZ1 with large disks is considered somewhat risky because, with the long resilver times that large disks imply, there's a significant possibility of an uncorrectable read error occurring during a resilver. Combine this with the fact that a RAIDZ1 array that has lost a disk no longer has any redundancy, and the risk of data loss becomes a concern. A RAIDZ2 array that loses a disk still has redundancy, so it's much more reliable.

Regardless of how you structure your array, you must backup any data you care about. RAID is not backup.

 

[Ganzir]

OK I searched a little an found this article: http://www.zdnet.com/article/why-raid-5-stops-working-in-2009/

So what you are telling me basically is that RAID5 (Z1) is no good and one should opt for RAID6 (Z2) instead.

So my 4 x 2 TB RAID5 needs to rebuild as 4 x 2 TB RAID6. Resulting in only 4 TB of storage space that can be used while the rest evaporates into redundancy and safety mechanisms.

So with my current configuration my used space rised from 50% to roughly 75%, leaving me with about 1 TB of usable storage. Meaning I can / should upgrade right now.

Furthermore how would you store a backup? Maybe on a second NAS of equal configuration? - That might be the savest thing to do indeed... - However I am sorry to say that this slightly exceeds my budget (read: the money I am willing to invest into a storage solution for home office purposes)

Nonetheless thanks for the advice.

EDIT:

What about SSDs are UREs also an issue here, or are they more save / insecure due to whatever reasons?

 

[Robert Trevellyan]

So what you are telling me basically is that RAID5 (Z1) is no good and one should opt for RAID6 (Z2) instead.

Not exactly, it depends on your risk tolerance, but it is important that you make an informed decision. For example, I'm currently running a simple mirror, which is not as durable as RAIDZ2, but:

1. I have spare disks on hand, burned in, so I can immediately replace one that fails.
2. Everything I care about on the array is backed up elsewhere.

 

[Robert Trevellyan]

What about SSDs are UREs also an issue here, or are they more save / insecure due to whatever reasons?

As far as I know, SSDs failures tend to be a bit different from hard drive failures. With hard drives, you often get early signs of failure, especially if you're paying attention. SSDs sometimes fail catastrophically with little or no warning.

 

[wblock]

So what you are telling me basically is that RAID5 (Z1) is no good and one should opt for RAID6 (Z2) instead.

Not quite. RAIDZ1 is okay up to a particular total size of array. There is some disagreement on that size, but let's say it's between 4TB and 12TB. That would be the total amount of space in the array, including redundancy. Of course RAIDZ2 can be used for smaller arrays also.

It's worth noting that RAIDZ1 and RAIDZ2 are not exactly equivalent to RAID5 and RAID6. ZFS has more in-depth knowledge about what is on the disks. So when a disk fails, it will only copy data that needs to be replicated to the new disk, almost certainly making it quicker and less wearing on the other disks than a less-intelligent hardware RAID controller that is going to copy the entire contents of a disk, used or not.

 

[Ganzir]

OK so I am going for Z2 on any future builds / upgrades.

I read something else: One should use ECC RAM since ZFS has no CHKDSK equivalent.

That beeing so, does it matter if it is unbuffered or registered ECC and if so, any thoughts on pros and cons?

 

[Stux]

Ideal situation is 6 disk Raidz2

Have you got room to add two disks?

But it comes down to you making an informed decision. Which is why I asked if you were aware of the problem, rather than lecturing ;)

Unbuffered or registered makes not difference except that you need to use what your motherboard requires.

 

[SebbaG]

There is also another safer way for exchanging disks in RaidZ1-setup described in http://doc.freenas.org/9.3/freenas_storage.html Chapter: 8.1.11. Replacing Drives to Grow a ZFS Pool. Therefore you need another spare SATA/SAS Port available. With this approach your resilvering process is definitely less risky.

But your plans for destroying and reorganizing it in a RaidZ2 sound even better ;)

 

[Ganzir]

Ideal situation is 6 disk Raidz2

Have you got room to add two disks?

I am using a Fractal Design Node 304 as casee. There should be space for two additional disks ....

What makes 6 disks ideal for Raid6 (Z2)?

Furthermore I read that one should use 1GB RAM per TB of diskspace ... does that mean diskspace total oder storage space?

So lets say I build a Z2 out of 6 10TB Disks, would that result in a RAM-requirement of 40 GB since I have 40 TB of storage space (and thus 48 GB since 40 GB is not possible) or in a RAM-requirement of 60 GB since the total disk space sums up to 60 TB ( and thus 64 GB since 60 GB is not possible)?

 

[MatthewSteinhoff]

Z2 out of 6 10TB Disks, would that result in a RAM-requirement of 40 GB since I have 40 TB of storage space

Rule of thumb. Give or take. More or less. Your mileage may vary.

FreeNAS will probably be reliable with 16GB RAM and 40TB when used as a simple storage device. Meaning, no Plex or other applications running locally and in a household environment with limited simultaneous access. Performance will likely be fine, too. Double that to 32GB and I wouldn't hesitate to recommend the configuration even with 60TB of active space.

Cheers,
Matt

 

[Ganzir]

what do you mean by "plex"?

 

[MatthewSteinhoff]

what do you mean by "plex"?

https://www.plex.tv/

Cheers,
Matt

 

[Ganzir]

So this plex thingy could be installed on a freenas ... however that would entail, that the mainboard provides some kind of graphics adapter because somehow I have to get the picture and sound to the TV (or whatever divice the media is watched on).

For 4k contend said graphics adapter would have to meet certain requirements and I do not know if an onboard chip could handle this, building a dedicated graphics adapter onto said mainboard, is to much of a hassle and crosspurposes the NAS which I wanted to be a data storage device with certain failsafes first and foremost.

I think I will continue to watch whatever is stored on the NAS on my PC from where I access the NAS, that worked rather well so far. - Thanks for the advice nonetheless.

 

[Ericloewe]

however that would entail, that the mainboard provides some kind of graphics adapter because somehow I have to get the picture and sound to the TV (or whatever divice the media is watched on).

No. FreeNAS does not support graphics output. Plex clients run on different devices.

 

[Ganzir]

So I would still have to use my PC and from there redirect the video output to my TV, than I do not see the advantage of plex, just so that everything looks nice, does not justify the work to set it up. I simly map my NAS to lets say Z:\ and access movies that are stored there via VLC and done.

I fail to see what would be better when using plex.

 

[MatthewSteinhoff]

I fail to see what would be better when using plex.

1. All of your media lives on FreeNAS.
2. FreeNAS hosts Plex.
3. You can stream to any device on your network (or the entire internets!) from Plex.
4. Plex encodes video appropriately for every platform.

FreeNAS is always on anyway. If you have Plex running under FreeNAS, you don't need to buy/configure/power a second device for transcoding and serving. Plex will stream to pretty much any device (Roku, smart TV, tablet, phone, computer, etc.) in that device's preferred format while simply hosting the files on a fileshare greatly limits what and where you can play those files.

Cheers,
Matt