Storage upgrade path?

[devilkin]

Hi,

1.5 years ago I went with a raidz1 over 4 6TB drives on my home server. Now I'm having two problems:

• out of space
• not 'mentally happy' with the only one disk redundancy level
• only 8 available SATA ports (but pci-e slots are available)

So I'd like to upgrade. I have backups of the necessities, not of everything (a lot of stuff on there is not of the kind that I *need* to back it up, but I do want it available as much as possible.)

I'm wondering what would be a good path to go to get a raidz2 or perhaps a mirror setup in there - preferrably I'd like to keep the 4 disks I have now as they still perform well (and have no errors)

Mirror also has only a one-disk parity option, so I think raidz2 would be a better choice. I don't know if it's possible to create a faulted raidz2, copy the date on, and then add the necessary additional disks to bring it up to parity? Or is there a bettery way to tackle this without having to buy too many disks that I'll never use again?

 

[blanchet]

Despite the apparent waste of space, a stripe of mirrors is the better choice for home users

• easy to expand even if you lack of disks slots. You need to buy only 2 new disks.
• lot of IOPS
• fast resilvering

You must have a backup, because raidz2 will not protect you from a human error, like deleting the wrong dataset.

 

[pschatz100]

Despite the apparent waste of space, a stripe of mirrors is the better choice for home users

• easy to expand even if you lack of disks slots. You need to buy only 2 new disks.
• lot of IOPS
• fast resilvering

You must have a backup, because raidz2 will not protect you from a human error, like deleting the wrong dataset.

I would not automatically agree that striping mirrors is a better choice than RaidZ2. It really depends upon your use case. RaidZ2 is more resilient than mirrors because any two disks can fail before you lose data. It is true that mirrors provide more IOPS, but many tasks such as serving media or doing backups will not benefit from the additional performance.

However, I emphatically agree that a good backup is necessary.

As for the OP's original questions - you didn't say how much space you want to end up with...

1. If you have a reliable backup, you can destroy the original pool and recreate it as a RaidZ2. If you add two more disks, you can configure a six disks Raid Z2 which will increase your raw storage from 18Tb to 24Tb, with two disk redundancy.
2. You could also purchase two new disks and configure them as a new mirrored pool. This will increase your capacity, but you will still have only one disk redundancy on each pool.

 

[devilkin]

I have (tested) backups in place of the critical data.

For space - well, the more the merrier ;) but at this sizepoint I do wonder what's worth more: the extra storage (so eg. raidz2) or going mirrors with faster resilvering. I woulnd't be entirely mad if I get more IOPS out of the pool - there are a bunch of VM's there too, which are at times rather slow.

 

[NugentS]

Honestly VM's = Mirrors for IOPS (or use SSD's)

 

[pschatz100]

If you want to support both VM's and storage, I would suggest configuring two pools: 1) one for the VM's, and 2) RaidZ2 for storage. The pool for the VM's could be a mirror of spinning disks, or an SSD.

On my system, I have one pool for jails and another for storage. My pool for the jails is where I would set up VM's (although I'm not running any at the present time.) While this is not strictly necessary, I like the idea of separating the data from the applications. It allows me to play around with jails and applications without potentially compromising my data.

I am a big believer in having two disk redundancy for storage, plus a backup. Redundancy becomes more important as disks become large because the resilvering process takes longer and puts more stress on your pool.

 

[devilkin]

Thank you all for the comments. In the end I migrated to 3 mirrors (2x14TB, 2x6 and 2x6), it's been the best decision ever wrt my VM's ;)