stripe to raid-z

[HaNue]

now setting is 20TB x 16 HDD strip

can i change raid-z1 or 2 or 3?

If impossible, can I add a drive in raid-z?
(eg : 20tb x 16hdd raid-z() > 20tb x 20hdd)

 

[Patrick M. Hausen]

You cannot change the layout of a vdev.
You cannot add disks to RAIDZ vdevs.

 

[HaNue]

You cannot change the layout of a vdev.
You cannot add disks to RAIDZ vdevs.

If so, do I have to set the maximum number of hard disks from the beginning and work?

 

[Patrick M. Hausen]

You can start with e.g. a 2 disk mirror and add a second mirror later. Or start with a 4 or 6 disk RAIDZ2 and add a second set of disks later.

Redundancy is per vdev. Pool capacity is the sum of all vdevs. You might want to read the ZFS primer.

 

[HaNue]

You can start with e.g. a 2 disk mirror and add a second mirror later. Or start with a 4 or 6 disk RAIDZ2 and add a second set of disks later.

Redundancy is per vdev. Pool capacity is the sum of all vdevs. You might want to read the ZFS primer.

If I make a z2 vdev pool with 14 x 20tb(240tb) of hard and later add 14 or 10 of them, would the parity hard be 4?

If i calculate with a simple mind
(Existing z2 14x20tb / parity 2hdd) 240TB + 240TB or 200TB
If it's not this calculation
240TB + 200TB or 240TB + 180TB?

 

[Patrick M. Hausen]

Each vdev will still have a redundancy of 2 drives. Lose one vdev and the entire pool is gone. So you can lose 2 drives guaranteed without problems. You can lose up to two more drives as long as they are in the second vdev. The redundancy does not add up.

14 is a bit wide by the way. I'd start with 2x 7-wide RAIDZ3 with 14 drives to configure. Depending on your use case, of course. If you need IOPS, don't use RAIDZ but mirrrors.

 

[HaNue]

Each vdev will still have a redundancy of 2 drives. Lose one vdev and the entire pool is gone. So you can lose 2 drives guaranteed without problems. You can lose up to two more drives as long as they are in the second vdev. The redundancy does not add up.

14 is a bit wide by the way. I'd start with 2x 7-wide RAIDZ3 with 14 drives to configure. Depending on your use case, of course. If you need IOPS, don't use RAIDZ but mirrrors.

I don't need iops, I just need a lot of capacity. It will be equipped with up to 28 pieces

If the parity hard is not accumulated, does it mean that there are only 2 parity hard even if I set it up and add the hard later?
(eg : 20tb x 14hdd after 20tb x 14hdd = 20tb x 26?)

 

[Patrick M. Hausen]

Please read the ZFS primer where all is explained in great detail. Repeating myself: redundancy is per vdev. Each RAIDZ2 vdev will have 2 disks "wasted". I avoid the term parity because ther are no dedicated parity disks in ZFS.