Slow speeds on new Zpool

[rpigg]

I had a True NAS install that had one pool that was using 95% of the available space as an isci share for a Veeam repository. Once the drive-in windows got full, I started experiencing speeds of less than 1 MB. I then realized that its best practice only to use 80 of the pool. So i removed the pool and created a new one, then i created a Zpool that's only 77% of the pool. I recreated my isci share, and it's only getting 2 MB now, so the speed did go up but not by much. Initially, I was getting .5 gig .

When removing the original pool, I just did an export and destroyed the data. Then I created a new pool and added a sized zpool.

The hardware is a PowerEdge R420 i has 4x 4 TB WD reds in it .

Does it take time to create the new Z pool? Should i have removed the pool differently ?

 

[Nick2253]

Some of the terms you are using are somewhat confusing. Let me make sure I understand what you are asking.

• "an isci share for a Veeam repository" Presumably you have a zvol that you are sharing to Veeam?
• "... created a new one, then i created a Zpool that's only 77% of the pool" Did you mean create a zvol that's only 77% of the pool?

Technically, there's no such thing as a "zpool". zpool is simply the command that you use to manage ZFS pools. As such, the correct term is simply "pool". On top of pools, you can create datasets or zvols in order to segregate and manage data.

Assuming that you are actually talking about zvols, then the correct best practice is to use 50% or less of the pool. This is because the zvol is a block device, and once you start getting above 50%, you will start getting excessive fragmentation, which will reduce performance. What really matters is the total amount of data, not really the zvol size, though for better managment, keeping the zvol at less than 50% prevents you from going over.

 

[sretalla]

my isci share

That will most likely be doing sync writes... you'll need to consider if you can use SMB which will allow async or look at managing the risk and setting sync=disabled on the zvol. (or look into a SLOG... but only after you read the rest of what I'll say below)

4x 4 TB WD reds

Are those RED Plus or RED? maybe those are SMR and not suitable for ZFS.

Also, only 4 disks... I'm guessing you used RAIDZ1 or RAIDZ2... not the best for what you're doing either:

The path to success for block storage

It seems like I haven't written a sticky for awhile, but just in the last week I've had to cover this topic several times. ZFS does two different things very well. One is storage of large sequentially-written files, such as archives, logs, or data files, where the file does not have the middle...

www.truenas.com

And finally, how are you connecting those disks? what's your controller and are you using hardware RAID (I think those Dell servers ship with RAID adapters unless you chose something else).