I just migrate from Unraid to Windows based Nas and evaluating storage solution. Now I'm trying to use DP and primocache together.
I have 2 SSDs(2TB each) and 3 HDDs(16Tx2 +14TB).
Why not using DP alone?
This is because:
1. DP SSD cache is only for writing.
2. I have VMs/Containers stored on the pool and I would like to accelerate their performance as well.
3. Though it's possible to store VMs/Containers to SSD directly, still I love the idea to gather all disks together.
So what I have tried till now?
1. allocate all HDDs to DP to create only one pool. Partition the both SSD to 2 volumes. One is for reading and one is for writing. Allocate the writing cache volume to DP and select them as SSD in SSD optimizer plugin. (I have some folders duplicated, so need 2 SSDs to support real time duplication)
2. allocate reading cache volumes on both SSD to Primocache L2 cache and set them to accelerate all underline HDDs. I load accelerate Reading preset as I only want to Primocache for reading.
Why I don't use Primocache alone for caching?
As I want to accelerate the whole pool, actually I have various types data on it. Some of them are very important and I also set duplication in DP. I heard that there is chance to break these data if Primocache failed to flush the cache to HDDs. Though I do have a UPS, still I don't want to risk my data in case of system crash.
Does the current solution fulfil my expectation?
Not sure. If I don't look at benchmark stats, it's OK. However, when I tried crystaldisk mark on both host and VM, I found that:
1. On the host, the acceleration is working. However it's more like purely accerlating by SSD. (~3000MB on seq read and write) I do have 4GB*2 L1 cache set for Primocache
2. On the VM, the reading acceleration is working. It's just like accelerated by RAM (20000MB+ seq read). However, seems writing is another story. It's ~300MB seq write.
So I would like to understand:
1. firstly, is there a better solution? Or am I doing anything wrong?
2. If no for 1#, is there a way to boost writing performance in VMs as well? When I use Primocache for both reading & wrting, inside the VM it can score ~3000MB/s for seq reading and ~1000MB/s for seq writing.