Do I need a Cache disk?

[mikeyosm]

My disk configuration as follows:

 

hardware: 2950x MSI x399 MEG Creation, 32GB @3200mhz

 

1 array disk (SSD) used for appdata and docker.

1 x SSD for VMs

2 x 3.5" HDDs for archive data

1 x 512GB nvme for Music Share

1 x 1TB nvme passed through to a W10 VM

 

Is there any reason why I should allocate a cache disk? Will it make much difference for file transfers between the W10 VM and UNRAID host?

 

I used the diskspeed docker to test the speeds of all my drives and worryingly the nvme 512GB drive tops out at 700MB/s reads. In Windows it tops out at 2-3Gbps.

What could be the issue?

 

Thank you

[trurl]

I assume the 2 HDDs are in the array. You don't specifically mention parity. Whether you have one now or you might add one later or maybe even never, that SSD array disk should really be your cache.

[trurl]

How are you using that other SSD and the 512GB nvme? As Unassigned Devices? Typically you shouldn't put anything but spinners in the array.

[mikeyosm]

32 minutes ago, trurl said:

How are you using that other SSD and the 512GB nvme? As Unassigned Devices? Typically you shouldn't put anything but spinners in the array.

Yes, just using them as unassigned devices.

[trurl]

This is still my recommendation.

43 minutes ago, trurl said:

You don't specifically mention parity. Whether you have one now or you might add one later or maybe even never, that SSD array disk should really be your cache.

39 minutes ago, trurl said:

Typically you shouldn't put anything but spinners in the array.

 

[mikeyosm]

1 hour ago, trurl said:

This is still my recommendation.

 

I have no need for parity and the only option I had at the time for an array was to include my 128GB SSD.

All other drives are configured under unassigned devices plugin. My questions is whether this is OK and whether assigning a SSD/nvme cache drive will actually help.

[trurl]

4 hours ago, mikeyosm said:

2 x 3.5" HDDs for archive data

Why would these disks not be in the Unraid array?

 

I don't understand your question. If your array only consists of a single SSD with no parity then cache is pretty meaningless and can't possibly have any effect. Sounds like you don't really have any idea what cache is.

[trurl]

If those archive disks are in the array then even then cache will have no effect. The whole point of cache is to have a disk that is not in the parity array and so isn't affected by parity write speeds.