LSFS L1 and L2 cache sizes

[Mitmont]

Hello and thanks for the forum site to get answers.

This question is about the correct amounts of L1 and L2 cache for a 9TB LSFS device. I know the max LSFS disk is 11TB. I know that we need to plan for the 300% usage so we're planning on a 3TB size useable space. We will enable Dedup. I also have seen the RAM requirement of 7.6GB RAM for 1TB LSFS partition which means we're going to need 68.4GB free RAM on the host for the 9TB LSFS disk.
So for L1 and L2 cache amounts. Will that be the 1GB per 1TB for L1 and 10% or 900GB for L2? Or is there a different size for LSFS vs the disk image that we've been using.
This is the first real look at the LSFS structure.

Second question. For the L2 cache. Can more than 1 LSFS disk use the same SSD disk if there's enough space to handle more than 1 of equal size or should each LSFS disk have it's own SSD?

Thanks

Mitmont

[Ivan (staff)]

Hello Mitmont,
Thanks for interesting in StarWind solution
Regarding your questions:
1)If you want to have 3 TB usable space on LSFS drive you have to create a 3 TB (not 9TB) LSFS device. It means you need 22,8 GB (with dedup) of free RAM on your hosts for the current device.
About L1 and L2 cache. The requirements for L1 is 1 GB RAM cache per 1 TB of storage. In your case, you should set L1 cache as 3 GB. For L2 cache you should use 10% of your 3 TB storage, so it should be a 300 Gb of L2 cache for the current device.
2) You can use one big SSD drive for L2 cache for many LSFS devices.
Also, you should create a 3 TB LSFS device and it can be overprovisioned in 3 times (to 9 TB), however, usable space would be only 3 TB.
In addition, be aware about dedup. It operates properly when you have many equal VMs with same data.
Have a good day!