StarWind SAN & NAS Free - L1/L2 Cache

[link855]

Hi All, I'm trying the new StarWind SAN & NAS Free appliance for the first time, I had previously make some experience with StarWind VSAN (installed directly on a physical windows based storage box) and the VSA linux based appliance.
I have notice that on StarWind SAN & NAS Free appliance, configuring a new virtual disk there is no option to use L1 RAM Cache or L2 Flash Cache on top of capacity drives as it is usually available on StarWind VSAN.
My ESXi server has SAS (capacity) and SSD (cache) drives directly attached to storage controller in target mode (no RAID functionalities). I don't know how I can leverage SSDs or RAM for accelerate IO operations.

Thanks and kind regards

[yaroslav (staff)]

Thanks for your question.
There is a way to add cache via config files. But here are my thoughts on why I would not do this for a standalone instance.
For best performance, I'd suggest using SSD array not as L2 cache but as underlying storage. L2 cache boosts only reads. See L2 cache operating principles here https://knowledgebase.starwindsoftware. ... rinciples/.
For performance sake, I'd suggest using the L1 cache in Write-back mode. But, since this is a standalone device, the write-back cache is not recommended due to the possible risk of data loss in case of service halt, unexpected shutdown of a VM, power outage or host PSOD as data in cache will be gone. The write-through cache will boost only reads.

If that is a lab environment, try this https://knowledgebase.starwindsoftware. ... rinciples/.

[link855]

Many thanks for your quick and detailed reply!
I would like your feedback about these points:
- Will be introduced in the future the cache option in the GUI (SAN & NAS appliance)?
- Do you have some details how to add cache via config files for current version?

Thanks again

[yaroslav (staff)]

Greetings,

I will log the feature request for this.
Please try this https://knowledgebase.starwindsoftware. ... rinciples/. Please also keep in mind the recommendations above.

[yaroslav (staff)]

Small update: No, we do not support L1/L2 cache in SAN & NAS, thus there is no option to create the configuration.

[thuong.huynh]

Small update: No, we do not support L1/L2 cache in SAN & NAS, thus there is no option to create the configuration.

can you explain more clearly, i'm using starwind vsan
How to enable l2 cache for existing HA target

[yaroslav (staff)]

Hi,

I think HA device might do it better.
L2 caching boosts only reads that generally are already OK due to HA reads from both nodes. It is not highly available, unlike RAM cache, so might be a source of inconsistency.

[thuong.huynh]

Hi,
Thank for information, but i want to enable l2 cache cho both node on HA 2 node.
you think l2 cache with Ha node will give lower performance than ram cache

[yaroslav (staff)]

Yes, RAM cache should be faster.
P.S. There might be leaks for RAM cache, though.

[thuong.huynh]

thank you,
but i still wonder if it is possible to create l2 cache for ha device and how to create it, does ram cache have any requirements on ram, ddr3 or higher
i follow this topic, but can't create it https://knowledgebase.starwindsoftware. ... dance/661/

[yaroslav (staff)]

IMO, I'd rather not use caching for production at all.

[thuong.huynh]

IMO, I'd rather not use caching for production at all.

Can you tell me why?

[yaroslav (staff)]

L2 is not a highly available RAM cache might be leaking.
For SSDs, RAM cache does not really improve anything from what I see in tests.