Fellow Forum  Members,

I know the UnRaid OS supports a single cache disk. But can it support 2 cache disks? I ask because the Cache Disk setup I am contemplating is one where Cache Disk #1 is used for docker apps to install to. And Cache Disk #2 is used as a data transfer drive to migrate files to UnRaid drives.  Can the UnRaid OS support such a Cache Disk configuration?  Below is a list of the hardware I'm contemplating to buy.  

 

Dual M.2 PCIe SSD Adapter Card

https://www.amazon.com/gp/product/B01FU9JS94/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

Cache Disk #1 = 1TB NVME

https://www.amazon.com/Samsung-970-EVO-1TB-MZ-V7E1T0BW/dp/B07BN217QG/ref=sr_1_3?dchild=1&keywords=1tb+nvme&qid=1590805806&s=electronics&sr=1-3

 

Cache Disk #2 = 4TB NVME

https://www.amazon.com/Sabrent-Rocket-Internal-Performance-SB-RKTQ-4TB/dp/B087N7HLRV/ref=sr_1_2?dchild=1&keywords=4tb+nvme&qid=1590805879&s=electronics&sr=1-2

 

Any opinions  on this dual Cache Disk setup I'm contemplating will be welcome. 

 

 

do you need two separate drives? is there a reason why one drive is 1TB and the other is 4TB? (I mean you obviously plan to dedicate one for one thing and the other for the other thing, but does it have to be so?)

 

I am basically doing what you're doing (dockers and data transfer) but I'm running a single cache pool with multiple drives in it.

1 hour ago, binar said:

I know the UnRaid OS supports a single cache disk. But can it support 2 cache disks?

Unraid currently supports single cache made of 1 or many disks.

Next release is meant to have multiple cache pools, which should fit your use case.

 

You could also look at unassigned devices plugin for adding disks that are not part of cache pool or array.

Thanks to all for your posts. According to the  UnRaid online manual (shown below as a copy and paste) the "Cache pool mode" utilizes an untraditional RAID 1.  So to answer my orignal question, the UnRaid OS does support mulitiple drives but using a hybrid form of RAID 1.  In short, I hope the next release comes out soon which Tjb_altf4 says will support multiple cache pools and do what I want it to do.

 

My reason for having two drives is because I want to keep all my docker apps contained in a single hard drive. And use the second drive as a temporary data parking place to slowly fill it up with data.  Once the second drive fills up the data is migrated over to an UnRaid drive. 

 

My hope is the UnRaid OS will not reject the PCI Adapter Card installed with two NVME drives and instead recognize it for use in a Cache Disk pool.  Can anybody out there confirm if setting up a Cache Disk Pool will encounter a problem if the PCI Adapter card shown in the link below is used?

 

https://www.amazon.com/gp/product/B01FU9JS94/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

Any opinions welcome.

 

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Cache pool mode

When more than one disk is assigned to the cache, this is referred to running in cache pool mode. This mode utilizes btrfs RAID 1 in order to allow for any number of devices to be grouped together in a pool. Unlike a traditional RAID 1, a btrfs RAID1 can mix and match devices of different sizes and speeds and can even be expanded and contracted as your needs change. To calculate how much capacity your btrfs pool will have, check out this handy btrfs disk usage calculator. Set the Preset RAID level to RAID-1, select the number of devices you have, and set the size for each. The tool will automatically calculate how much space you will have available.

 

9 hours ago, binar said:

Can anybody out there confirm if setting up a Cache Disk Pool will encounter a problem if the PCI Adapter card shown in the link below is used?

Should be fine as long as support by your hardware, the adapter is transparent to the OS.

If that is want to do why not mount one of the drives as an unassigned device and install your dockers there. Then use the other as a normal cache drive?