Raidz2 4 drives total (2 drives for data and 2 for parity)

[cgigeek]

Hello, been reading this forum for a while, finally ready for my first question.

Discounting any economic or space ratio benefits ,
and knowing well I do need to backup my pools:
are there any cons or setbacks of setting a RaidZ2 with 4 drives total (2 drives for data and 2 for parity)

What I am trying to achieve is to be able to replace any of the 2 data drives at any given point.

 

[BigDave]

What I am trying to achieve is to be able to replace any of the 2 data drives at any given point.

If the term "at any given point" means drive failure, that's fine.
Just keep in mind, once a RAIDz2 Vdev is created, the ONLY two ways to grow that pool,
is to replace each of the drives with larger capacity ones, or add another Vdev.
See the links in my signature for more valuable information.
Dave

 

[diedrichg]

Read here for a spreadsheet to help you with the economics/pool size.

https://forums.freenas.org/index.php?threads/38092/
ZFS Drive Size and Cost Comparison Spreadsheet

 

[danb35]

are there any cons or setbacks of setting a RaidZ2 with 4 drives total (2 drives for data and 2 for parity)

To directly answer your question, no, there aren't. And just in case you aren't clear on this, RAIDZn doesn't use dedicated parity drives; each drive stores both data and parity (though it's often simpler to talk of "two parity drives"). A four-disk RAIDZ2 pool will survive the loss of two disks without data loss.

 

[cgigeek]

thank you all
guess is a bit slower then raidz1 but I can live with it

 

[maglin]

Speed would be the same. With only 4 disks why not go with RAID10 and run stripped mirrors. It will be faster all around while giving the same amount of usable space. Also expansion is easy as you can expand with another 2 disk vdev.


Sent from my iPhone using Tapatalk

 

[Robert Trevellyan]

With only 4 disks why not go with RAID10 and run stripped mirrors.

One reason would be that it's less reliable, but that doesn't mean it's wrong, it just depends on your priorities.