Hi all,

 

How is the Raid performance on UNRAID?

 

For the following question : I do NOT care about redundancy or backups (only space and performance) 

 

I have 2 identical machines - each with 12*8Tb drives.

 

One is running Ubuntu 20.04 with Raid 0

/dev/md1:
 Timing cached reads:   10994 MB in  1.99 seconds = 5523.34 MB/sec
 Timing buffered disk reads: 4042 MB in  3.00 seconds = 1347.14 MB/sec
root@Storage4:~# sudo hdparm -Tt /dev/md1

 

Identical machine (UNRAID OS)

/dev/sda1:
 Timing cached reads:   9340 MB in  1.99 seconds = 4688.61 MB/sec
 Timing buffered disk reads:  30 MB in  3.21 seconds =   9.35 MB/sec
 

Both machines are Raid0 (as performance is required over backups(I don't mind if I lose all data))

As you can see the performance of Buffered Disk Reads are not even close to being comparable!!

 

Image attached of the setup in UNRAID

 

Have I setup UNRAID Array correctly as Raid0?

I'm beginning to think I have not!!!

 

Thanks for any help/suggestions you can offer...

Unraid does not implement what is normally meant by RAID0 (and hence the name).  Unraid will never have the performance of a more typical RAID system for a number of reasons

• Each array drive is a self-contained filing system and so files cannot span drives and striping cannot be used.  Reads are therefore limited to the read speed of any drive involved in the read.
• For writes Unraid updates parity in a completely different way to a standard RAID system which leads to significant performance overhead. 

The techniques used for Reads and Writes are described here in the online documentation that can be accessed via the Manual link at the bottom of the Unraid GUI.

 

If you want to use Unraid with performance as the main criteria then you should not use the main array for the data but instead look into use Unraid BTRFS pools as these operate more like a traditional RAID system.

Thanks itimpi

 

Ill read up on the links you recommend!

 

Appreciate the fast response!