Hey all,

 

I just built a new unRAID server to replace an old Windows File server I've been using at home. It is equipped with 6x 6TB HDD's and 6x 800GB SSD's.  I got everything installed and unRAID is operational. I was trying to figure out how I wanted to allocate the disks to my array and got kind of stuck. I was reading the docs about parity drives and cache drives and I'm not sure what the best thing to do here is.

 

• I would like to leverage the speed of my SSD's but does it make sense to add all 6 SSD's as cache? I think I want some cache for faster perceived writes to my big 6TB disks, and I would want at least RAID1 on the cache, so I would need at least 2 allocated to cache.
• I would like to have some of the SSD's be permanent storage for VM's and other IOPs intensive workloads, how can I ensure they are used as such?
• How many Parity drives do I need? Is a single 6TB drive OK?

Please advise, unRAID is completely new to me.

 

Thanks!

Edited April 15, 20206 yr by vegetablebreakfast

26 minutes ago, vegetablebreakfast said:

I would like to leverage the speed of my SSD's but does it make sense to add all 6 SSD's as cache? I think I want some cache for faster perceived writes to my big 6TB disks, and I would want at least RAID1 on the cache, so I would need at least 2 allocated to cache.

A cache pool can have as many SSDs as you wish.  Of course, in a RAID 1 configuration, half the capacity in the pool is available for caching and the other half is a mirror.

 

Your appdata (Docker containers), system and iso (VM) shares should ideally be on a cache SSD/pool or unassigned device (see below).

 

In unRAID 6.9, multiple cache pools will be supported.  This will allow you to designate different cache pools for different uses.

 

You can also assign SSDs as unassigned devices with the Unassigned Devices plugin.  This is commonly done for VMs so all files related to a VM are on an SSD and do not cause array drives to spin up.  Some even go so far as to have a separate SSD for each heavy use VM.

 

1 Parity drive is plenty to protect six data drives in the array.  Most start considering dual parity at 8 data drives and above.

 

Edited April 15, 20206 yr by Hoopster

Thanks Hoopster.

 

If I did put all 6 SSD's into one cache, could I use RAID 5 or 6 to protect that data?  Could I use it for share caching as well as VM storage? I'm trying to think of the most flexible use of all 6 drives.