Raid Question

[Soid]

Im preparing to set up a new HexOS NAS with raid 5.  Im fairly inexperienced with raid configs and never worked in truenas. My old NAS has a 4 TB and an 8 TB (in raid 1… I intended to upgrade the 4 but never got around to it). Trying not to waste them in my new setup. 

 

From my Wikipedia-fu, my understanding is the drives need to be the same size.  So Im thinking I could Raid 0 the 4+8 and nest that with two new 12s in Raid 5 for 24 TB of storage? Is that off base? Am opening a can of worms I’d best not open?
 

It’s not a huge burden for me to buy another drive, I’d just rather use what I already have. If the 4 or 8 fails (the 4 is a 7 yr old ironwolf) just replace it with a 12 down the line. 

[Blue4130]

18 minutes ago, Soid said:

Im preparing to set up a new HexOS NAS with raid 5.  Im fairly inexperienced with raid configs and never worked in truenas. My old NAS has a 4 TB and an 8 TB (in raid 1… I intended to upgrade the 4 but never got around to it). Trying not to waste them in my new setup. 

 

From my Wikipedia-fu, my understanding is the drives need to be the same size.  So Im thinking I could Raid 0 the 4+8 and nest that with two new 12s in Raid 5 for 24 TB of storage? Is that off base? Am opening a can of worms I’d best not open?
 

It’s not a huge burden for me to buy another drive, I’d just rather use what I already have. If the 4 or 8 fails (the 4 is a 7 yr old ironwolf) just replace it with a 12 down the line. 

That would be a bad idea. It would negate any safety that raid 5 gives you. If one of those two drives fail, the whole array would be SOL.

[Soid]

I'm thinking the 4+8 could hold the place of one 12 TB drive. Structure would look like:

 

                 | - Raid 0 - 4TB+8TB = 12 TB

Raid 5 --- | - 12 TB

                 | - 12 TB

 

It looks to me that any one could fail and still maintain the two. But your gut reaction tells me I'm playing with a can of worms that could have unforeseen consequences, and possibly not rebuild correctly. It's probably best that I don't try to be clever when I don't know what I'm doing.  I can find another use for the drives. 

 

[Blue4130]

29 minutes ago, Soid said:

I'm thinking the 4+8 could hold the place of one 12 TB drive. Structure would look like:

 

                 | - Raid 0 - 4TB+8TB = 12 TB

Raid 5 --- | - 12 TB

                 | - 12 TB

 

It looks to me that any one could fail and still maintain the two. But your gut reaction tells me I'm playing with a can of worms that could have unforeseen consequences, and possibly not rebuild correctly. It's probably best that I don't try to be clever when I don't know what I'm doing.  I can find another use for the drives. 

 

Ah yea, that would maintain redundancy, but it would be pretty janky. If it was me, I'd opt for a third 12 tb drive. Use the old drives as a backup of key files.

[Kilrah]

23 hours ago, Soid said:

                 | - Raid 0 - 4TB+8TB = 12 TB

Raid 5 --- | - 12 TB

                 | - 12 TB

 

 

That RAID0 would give you 4TB 8TB, not 12.

 

With that set of disks Unraid would be a better choice. I also doubt HexOS will let you make "weird pool-in-pool" configs at least at this stage.

[Soid]

5 hours ago, Kilrah said:

That RAID0 would give you 4TB, not 12.

 

With that set of disks Unraid would be a better choice. I also doubt HexOS will let you make "weird pool-in-pool" configs at least at this stage.

Re-read the Raid-0 Article, and you're partially right.  It looks like it'd end up being 4+4 (the other 4 on the 8 would be wasted), so it wouldn't work anyway.

 

If I can find a good deal, I'll just buy three 8 TB drives and have 4-8 gig drives in Raid 5, and that should still give me the same space. Though it looks like the good deals on refurbished drives are on big ones.

[Jarsky]

9 hours ago, Soid said:

Im preparing to set up a new HexOS NAS with raid 5.

So Im thinking I could Raid 0 the 4+8 and nest that with two new 12s in Raid 5 for 24 TB of storage? Is that off base? Am opening a can of worms I’d best not open?

 

If you RAID0 2 drives; they will be the size of the smallest disk - that is it will only be an 8TB stripe. 

You would need another 12TB drive to setup a redundant raid (or whatever they call it in HexOS) with the full 24TB of storage; otherwise you will be limited to an 16TB RAID-Z1

 

You do need a "hardware" RAID for the RAID0 as it needs to be pre-OS. I've build a hybrid raid before using Intel RST to RAID0 2 x 1TB; and then used Software RAID to mirror that with a 2TB disk.

 

Using your diagram it would basically look like this:

 

                 | - Raid 0 - 4TB+8TB = 8 TB Usable

Raid 5 --- | - 12 TB Drive (8 TB Usable)

                 | - 12 TB Drive (8 TB Usable)
 

It would really be advisable to just get another 12TB drive if you can; then you'll have the full usable space without having to go through all the headaches of replacing drives; resilvering and expanding the VDEV/Dataset.