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"growing" a RAID array?

Posted: 13 Jul 2015 21:28
by Southcross
I'm still contemplating my options... purchase a stack of large hard drives (my wallet does not like this idea)... or buy several smaller HDs, perhaps a stack of 1TBs, then add drives as money allows. I would love to get a bunch of 1TB 5400 RPM laptop hard drives and a 5.25" to 4-2.5" bay adapter.

Can a RAID array be created (Software or ZFS) with 3 or 4 HDs, then be able add 1 or more at a time and grow the array without re-creating it?

Re: "growing" a RAID array?

Posted: 13 Jul 2015 21:36
by raulfg3
no, but please read this powerpoint to understand how ZFS works.

https://forums.freenas.org/index.php?th ... oobs.7775/

Re: "growing" a RAID array?

Posted: 13 Jul 2015 21:40
by erico.bettoni
Like this?
backupNAS.jpg
This is my backup NAS. I usually add drives in groups of 3, adding a top level raid-z1 each time.

Re: "growing" a RAID array?

Posted: 13 Jul 2015 22:13
by Southcross
erico.bettoni wrote:Like this?
backupNAS.jpg
This is my backup NAS. I usually add drives in groups of 3, adding a top level raid-z1 each time.
yeah, that is exactly what I'm thinking... they even make them capable of holding 6-drives per 5.25 bay :)


ok... ZFS is very very new to me. If I understand this correctly, in a 3-disk RAID they can grow 3 (or more) disks at a time? x3 1TBs would net 2TB storage, 3x more would net 4TB, 3x more , would net 6TB. or would a 3-disk sub-array of 1TBs only net 1TB storage?
each sub-array would be protected from 1 failure?
and if the sub-array totally fails, the entire ZFS array fails

Re: "growing" a RAID array?

Posted: 13 Jul 2015 22:29
by erico.bettoni
You can grow in two ways:
- Adding top level vdevs
- Replacing all disks in a vdev with larger ones (when you replace the last one the vdev will grow)

Raidz1 provide one disk fail tollerance. This is ok for me on my backup NAS. I also use 3 disks on the raidz1 so its cheapper to grow than 5 disks for example, altough I lose more space to parity than 5 disks.

On my main NAS I use raidz2.

And read the link raulfg posted. :)

Re: "growing" a RAID array?

Posted: 13 Jul 2015 23:25
by Southcross
this is for my home NAS server... I'm combining two file servers: a <500GB FreeNAS (the original, before the split of FreeNAS/NAS4Free) and a Windows Based 2TB Media Server (for HTPC streaming)... I am not too concerned about a failure of the HTPC Media, it would suck to re-rip all of my DVDs, the stuff I can't loose will be hard-copied to a 1TB spare and off-site stored... the <500GB of home data is now migrated to a Software RAID-1 pair of 2-TBs, which are then Rsync'd to offsite Cloud storage. I'd like to make my Media Storage to be growable, which ZFS/RAIDZ1 now sounds like the ticket :)

Re: "growing" a RAID array?

Posted: 13 Jul 2015 23:33
by Southcross
erico.bettoni wrote:Like this?
backupNAS.jpg
This is my backup NAS. I usually add drives in groups of 3, adding a top level raid-z1 each time.
now the question I have though... are you using NAS grade 2.5" drives, or off the shelf laptop drives?

Re: "growing" a RAID array?

Posted: 14 Jul 2015 05:30
by lexiaa
the backup space can be saved if you use the right tool. I have tried one. Aomei Backupper a freeware.

Re: "growing" a RAID array?

Posted: 14 Jul 2015 15:15
by erico.bettoni
I'm using the cheapest hard drives I can find, EXCEPT seagate ones.

Re: "growing" a RAID array?

Posted: 14 Jul 2015 19:28
by Southcross
LOL... Seagate...
I keep looking at Seagate NAS drives, their prices look great, then I keep reminding myself that they are Seagates LOL

I just picked up a 8-port PCIe x4 controller for stupid cheap... now I have to decide if and what I want to pull the trigger on stacks of drives

Re: "growing" a RAID array?

Posted: 20 May 2016 03:00
by MustangPilot
On the same subject of 'growing' your raid. Is it possible for me to go from a RAID1 - Mirror (2x4TBNASdrives) to a RAID10 (4x4TBNASdrives) without losing my data, or is it possible but discouraged? I have a moderate amount of data already on the server, and I could probably data dump and start fresh with RAID10 but only if it will make a noteable performance or data integrity difference. Btw the new drives are identical to the drives in the existing array. 4xHGST Deskstar NAS 3.5-Inch 4TB 7200RPM SATA III 64MB Cache Internal Hard Drive Kit (0S03664)