Adding/Extending L2 cache

[pstoianov]

G'Day everyone,

I use two node failover cluster with StarWind V8 build 7852 in production.
How I can add L2 cache to each HA-disk?
Is it possible later to expand the cache?

I saw a bug in the latest v8-7852 release where L2 cache is not shown on the right side of the panel. Have you seen that?

[javasdk]

the build 7923 also
the L2 only show on thin disk , but thick disk cannot show

even the thin disk show L2 cache , it is N/A (sometime the image name) , not the size of the cache

I see the release notes for the L2 known issue : L2 cache: stability issues found in current implementation.
is it related?

[Oles (staff)]

Hello everyone!

We have some issues related to L2 cache in Write-Back mode, thus, meanwhile we recommend using L2 cache in Wright-Through mode only.

To apply L2 cache on existing devices, please follow next steps:

1. Create 1 device for L2 cache of necessary size. Do not attach it to any targets. Location of L2 device’s .img and .swdsk files should be path to your SSD drives’ array

2. Stop StarWind service

3. Open the corresponding .swdsk file of L2 device and copy the section that says this:

<storage id="3" name="My Computer\D\img\L2-Storage11.swdsk" type="device" lun="0">
<interval size="XXXXX" units="MB"/>
</storage>
Note: paths, size and storage id will differ in your case.

4. Open the corresponding .swdsk file of your main device and paste this section there between <storages>and </storages> tags.

5. Now add the following section keeping “storage_ref id” the same as “storage id” above (in this case it is 3):

<cache type="write-through" size="XXXXX" units="MB" level="2">
<storage_ref id="3"/>
</cache>
This should be added in-between <caching> and </caching> tags.

6. Start StarWind service

7. Now L2 device should actually disappear from SW console.

Please note that, the amount of L2 cache should be equaled to 10% of your storage.

L2 cache may not be shown as L1 cache only in case when you create a device, which has L1 cache disabled and L2 cache enabled.
If you create a device with cache enabled, and it is not shown in SW console, please submit a support ticket and attach SW logs to it.

Thank you.

[pstoianov]

Thank you Oles! Succeed to add L2 cache in WT mode.
I was now wondering what will be the impact to cover just 3%-4% as L2 WT cache from the total storage? Is there any impact?
VMware's VSAN recommends at least 10% just because their VSAN has very slow performance if cache is below 10% - works as designed.

[Oles (staff)]

Pstoianov,

The benchmarking that you have described is already in roadmap. Stay tuned