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Change JBOD to RAIDZ (5)?

Mincading

57 months ago

Hey guys, 8 months ago I decided to build a simple home server (FreeNAS) using the following drives: 1x 3TB 1x 1TB

*2x 500GB

*3x 250GB

Odd set of drives but I wasn't expecting on adding so many drives. Total drive (JBOD) Capacity is around 5.12TB. My question is,

Is there an easy way to change the configuration to raidz? (8x3TB in the future).

The current solution i can think of is 1.offlining the 4 lowest capacity drives, and swapping the 4 drives for 4x 3TB drives.

2.Initiate a new volume using RAIDZ (Essentially raid 5?) and transfer data from JBOD to new volume.

3.Offline the remaining JBOD drives and then installing 4 more 3TB and adding it to the raidz array.

Is this possible?

This machine is currently using an A85X AMD chip set with an A10 6800k apu downclocked to 2.2GHz. Lemme know if you need more information. Thanks all!

link to the actual build

Comments

  • 57 months ago
  • 2 points

If you insist on RAIDZ1, four drives is a sub-optimal configuration. Optimal RAIDZ1 setups are 2, 3, 5, or 9 drives per VDev.

But you shouldn't be using RAIDZ1; you should budget for RAIDZ2 (optimal setups: 3, 4, 6, or 10 drives per VDev). The three-drive setup is pointless; I'd recommend six.

Once a VDev is created, you can't add more drives to it later. You can later make a VDev bigger by replacing each drive within it with a larger one, but you can't add more drives; you can only create new VDevs. Plan ahead. This slideshow should help clarify the rules and restrictions on VDevs and zpools.

As for the existing drives, it all depends on how you have them configured. If you have them set up as one drive per VDev (no redundancy), and you have enough SATA connections, you shouldn't even need to offline them. You can keep them spinning and copy directly from them to the new drives. (EDIT: On the other hand, if they're all separate VDevs, but you added them all to a single ZPool, then you may be screwed, and can't offline any of them.)

RAIDZ1 is discouraged, as you only have one disk's worth of redundancy, and uncorrectable read error rates haven't kept pace with drive capacities. Drive failures tend to be temporally coherent (drives installed at the same time will tend fail around the same time). If a drive fails, the replacement drive will need to be "re-silvered." This process pretty much involves reading the entire surface of all the other drives in the VDev. It is usually during this very intensive process that a second drive takes an uncorrectable read error, and your entire pool is then toast. So don't skimp; go RAIDZ2.

And make sure you have enough RAM. 8 GiB of ECC RAM is the absolute minimum for recent releases of FreeNAS.

  • 57 months ago
  • 1 point

wow. Just wow. You explained it perfectly. Thanks a lot man, You the man! Check your inbox :)

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