3 X 1TB NVME Drives For Cache Advice Please?

[mbc0]

Hi,

 

I currently have 2 X 1TB NVME Drives as a btrfs cache pool but now have another 1TB spare so considering my options.

 

I would not want to have less than 1.5TB useable space in my pool but don't think 3 X 1TB drives can be used in any way to give me that space with protection.  I was just thinking what a nightmare I would have if one of these drives goes down losing everything on my cache pool so would like to find the most economical way to protect my cache pool even if it means buying more/different drives.

 

Can anyone offer any advice/suggestions please?

 

Thank you

[jmztaylor]

One option is to just use the 1 drive in another cache pool and only use that for data that will be pushed to array quickly.  And leave important stuff like VMs and appdata on the 2 drive pool.  

[itimpi]

5 hours ago, mbc0 said:

Hi,

 

I currently have 2 X 1TB NVME Drives as a btrfs cache pool but now have another 1TB spare so considering my options.

 

I would not want to have less than 1.5TB useable space in my pool but don't think 3 X 1TB drives can be used in any way to give me that space with protection.  I was just thinking what a nightmare I would have if one of these drives goes down losing everything on my cache pool so would like to find the most economical way to protect my cache pool even if it means buying more/different drives.

 

Can anyone offer any advice/suggestions please?

 

Thank you

If your current pool is using the BTRFS variant of RAID1, then adding the 3rd 1TB drive would give you 1.5TB of useable space.  BTRFS does not require you to have an even number of drives.  
 

One thing to be aware of is that with an odd number of drives in a BTRFS pool the used/free space values in the GUI tend to be off (but get more accurate as the pool fills up).

[mbc0]

18 hours ago, jmztaylor said:

One option is to just use the 1 drive in another cache pool and only use that for data that will be pushed to array quickly.  And leave important stuff like VMs and appdata on the 2 drive pool.  

This sounds interesting, do you have any info? is it a 2nd cache pool?

 

[mbc0]

13 hours ago, itimpi said:

If your current pool is using the BTRFS variant of RAID1, then adding the 3rd 1TB drive would give you 1.5TB of useable space.  BTRFS does not require you to have an even number of drives.  
 

One thing to be aware of is that with an odd number of drives in a BTRFS pool the used/free space values in the GUI tend to be off (but get more accurate as the pool fills up).

Thank you, this may also be an option!

 

[jmztaylor]

17 minutes ago, mbc0 said:

This sounds interesting, do you have any info? is it a 2nd cache pool?

 

 

Yeah you just select new cache pool when array is stopped and assign a device to it.  

[trurl]

15 minutes ago, mbc0 said:

This sounds interesting, do you have any info? is it a 2nd cache pool?

Unraid 6.9 and up allows multiple pools. Cache is just the name of the first pool most people have, you can name pools however you wish. A pool with multiple disks must use btrfs.

 

https://wiki.unraid.net/Manual/Storage_Management#Pool_.28cache.29_Operations

[mbc0]

2 hours ago, trurl said:

Unraid 6.9 and up allows multiple pools. Cache is just the name of the first pool most people have, you can name pools however you wish. A pool with multiple disks must use btrfs.

 

https://wiki.unraid.net/Manual/Storage_Management#Pool_.28cache.29_Operations

Thank you, I will have a read!