Question about cache pool

[m0ngr31]

I have 2 slots left on my NAS I can put SSD drives into for a cache pool. I have 3 SSDs kicking around I was thinking about using: 128GB, and 2x 32GB.

 

What would be the best setup? A RAID1 for maximum space and speed? But then I'm hosed if one goes bad right? All of my dockers and stuff will be gone? Should I just run a RAID0 with the 32GB ones and hope it's enough space?

[trurl]

Since you don't have enough slots for all 3 I would just go with the 128 by itself.

 

If you did use all 3 disks in btrfs raid1 you would get redundancy, but only 64GB total capacity. raid0 would give 96GB but no reduncancy except metadata. Best for capacity would be "single" for all 192GB but no redundancy.

 

http://carfax.org.uk/btrfs-usage/

 

Lots more about cache in the FAQ:

 

 

Probably a good idea to have backups of appdata and VMs anyway, which you can get with CA Backup plugin.

 

[m0ngr31]

So even in RAID1, the metadata has redundancy?

[gubbgnutten]

Sounds like you have RAID 0 and 1 mixed up, @m0ngr31...

[m0ngr31]

On 5/2/2017 at 0:26 PM, trurl said:

raid0 would give 96GB but no reduncancy except metadata

 

I was just trying to clarify this since it didn't make sense to me.

[JorgeB]

 
I was just trying to clarify this since it didn't make sense to me.

With brtfs raid you can have raid0 for data together with raid1 for metadata.