I'm currently using 4 x 4TB WD Nas drives split in 2 RAIDZ1 pools.
I'm planning on buying 2 more, and was wondering if I should combine them all to a RAIDZ2 og RAIDZ3 pool.
wouldn't that require backing all this data and then switching it's type?
Yes, I could rsync all the datasets to Amazon S3 or something. Or upload the files with Windows to another cloud service ect.
Should probably do that anyways if it's important
But do you really need the space now? Because upgrading to fewer larger capacity drives is possibly the way to go to keep your array with as few drives as possible
Both my raidz1 pools are almost at 80%.
Yes, I have the most important files backed up to the cloud, my desktop, and a harddrive that is not connected to anything.
I guess my question is: Is 3 RAIDZ1 pools less secure than either a RAIDZ2 pools with 6 4tb drives or RAIDZ3 with 6 4tb drives.
more drives is more points of failure for me at least, probably fine overall though to just add on an extra set of drive in their own pool
1 Like
more drives in general means failure but more drives also leads to things like bit-rot.
more drives are fine if you have something like btrfs running is something like raid 5 or 6 so that some drives can fail.
but this is coming from the person who a has server with 5 drives in raid 0
Cool. Will probably just add them as their own pool. which I will proudly name "Sevastopool" Yes I'm an Alien fan :)
Just to be clear, you have two pools of 4x4TB RAIDZ1 (RAID 5)?
RAID 5 is not longer considered safe in an enterprise environment and if I understand you correctly, you already have two parity disks so switching to RAID Z2 makes even more sense. This would net you more space and better redundancy, plus better read speeds.
Would require rebuilding the array right?
Yes you would have to rebuild your array but I think the headache would be worthwhile in your case. You would have the same space before adding any new drives, if you added two new drives as mentioned you would have 8TB of additional space, 32TB total with RAIDZ2 with 10 drives. But most importantly you would have double parity vs single parity on three pools, this is critical.
I have a total of 4 drives, 2 pools consisting of 2 4tb drives each in raidz1.
Sorry I confused RAIDZ1 (Mirroring) with RAIDZ (RAID5), I am used to terms like RAID1 or just mirroring.
Anywho you have 1 parity disk for each pool now which is not preferred and if you are planning on adding two more disks this puts you in the perfect situation to upgrade your capacity AND redundancy.
So right now you have 8TB usable over 4 drives. If you add 2 additional drives in RAIDZ1 (mirroring) you would be adding an additional 4TB, however with RAIDZ2 you would get 8TB and double parity.
RAIDZ1 (Mirror) - 4 drives = 8TB (Two pools, one drive failure)
RAIDZ1 (Mirror - 6 Drives = 12TB (Three pools, one drive failure)
RAIDZ2 (RAID6) - 6 drives = 16TB (One pool, two drive failure)
So as you can see you net an extra 4TB AND double parity (2 drive failure). The only negative impact is write speeds but I wouldn't worry about this too much, especially if you are on 1GbE.
1 Like
Thanks!
I'm not clear what you mean... Z1 requires 3 drives. You're effectively talking about RAID 5. What you're talking about sounds like a ZFS mirror.
This would mean you're looking at an effective 8TB of storage between those pools.
Also, your redundancy is a single drive/pool.
If you were to upgrade to 6 4TB drives and simply put the new drives into a mirror you would be looking at 3 mirrors with a single drive redundancy each. This would give you an effective capacity of 12TB.
If you instead went with a ZFS Z2 pool you would have an effective capacity of 16TB and two drives of redundancy. You could further add to your redundancy by using ZFS Z3(RAID 7) which would give you a capacity of 12TB and 3 drives of redundancy.
To answer your question. Yes. 3 MIRROR pools are less secure than a Z2/Z3 array.
3 ZFS mirrors will allow a maximum drive failure of 1 drive per pool before the array fails. This means that if you were to lose 2 drives and they happened to be in the same pool, you're going to lose that pool. If you instead went with a Z2/Z3 you could lose up to 2/3 drives respectively and still have all your data secure.
1 Like
Yes, sorry I meant ZFS mirror. Thanks for the clarification!