Hi all,

 

I am currently using unraid for about a year, and now going to add some disks (now having 1 8TB parity + 1 8TB array) to it, and since now unraid supports zfs, so now i wish to have zfs format.

 

Now here my situation:

 

1. I am going to add 4 x 8TB disk.

2. I am going to setup it as a zfs pool with raidz.

 

So my question is:

 

1. Since raidz provides a similar function as parity, do I still need parity drive?

2. If yes, based on my research, parity must be the largest or equal space disk, so if i setup a disk pool (in this case it will be 8tbx3 = 24tb), does this make sense?

3. My previous 8TB drive, most of resources are jellyfin media, would it be nice if i reformat all to zfs, and create a raidz, without the parity?

4. Currently i having an issue with write speed, if with parity drive, my write speed from other computer to unraid will be limited to 70mb/s +- (1gbps lan network), but previously there is no speed limit before i added parity drive. Is this caused by parity?

 

 

Sorry for my poor knowledge, i really cant decide what to do now. I wonder if there is some mistake, i have to take a long time to do data migration. Hope that some pros could give me a good solution.

 

Thanks in advance.

Unraid "Array" disks can be formatted as ZFS but they exist as stand alone ZFS disks, they can't be RAIDZ. If you want to benefit from RAIDZ the disks need to be a pool, not part of the Unraid "Array". That means that they won't be protected by the parity disk so if you need protection for drive failure you need to have multiple disk in the pool and select the level of RAIDZ you want.

 

If you format your existing 8TB Unraid data drive to ZFS you will be able to take advantage of replication tasks from a ZFS pool. The existing 8TB drive data will still be protected by the parity disk if it is formatted as ZFS.

 

You should get about 110 MB/s over gigabit using SMB. If the share that you are writing to is set to Array Only instead of Cache Primary and Array Secondary then you will write slower because the data is going straight to the array disk and the server is doing parity calculations at the same time. Depending on the speed of your HDDs; to maximise your network transfer speed you might need a an SSD cache drive and set the share you are writing to as Cache primary then Array secondary. The data will go to the Cache drive first then the Mover task will move the files to the array drive at the end of the day or custom time that you configure it to run.

 

Watch and pay attention to these two videos to get a better understanding of how ZFS works in Unraid:
Spaceinvader One - How to Reformat (ZFS) and or Upgrade a Cache Pool in Unraid

Spaceinvader One - Array Disk Conversion to ZFS or Other Filesystems - No Data Loss, No Parity Break!