Enabling L3 Cache and populating it

Hi Guys,

I'm planning to enable L3 Cache on several upgraded clusters. And have some questions regarding that process.

Current Situation:

- Freshly upgraded Clusters on 7.1.1.x

- MultiScan Jobs etc. are finished

- The Clusters are productive for our customer

- We use our SSDs for Metadata-Read acceleration.

- The current workload is mostly random access and files with <128K are also quite often in use --> we should profit from L3 Cache

- Smartpool license is NOT in use

- on the clusters is only one nodepool used

- the SSDs have space left

Planned process:

isi storagepool nodepool modify -l3 true

wait for jobs to complete

profit.

Since the L3 activation process requires the metadata copies to be evacuated from the SSD with SetProtectPlus and FlexProtect before reformatting the drives as L3 cache, we won't profit from metadataread nor L3 cache until reformatting finished. I want to minimize the performance impact for our customer and thus have the following questions

L3 Cache is populated by evicted blocks from L2 cache. My plan is to have the L3 Cache populated with metadata at the time the customer accesses the data (after the weekend), so he has no performance impact by not having metadataread enabled.

Can i force a population of L3 cache with metadata by just stupidly doing treewalks (via SMB/NFS)?

In my mind the metadata will reside either in L1/L2 or L3 Cache after a complete treewalk (and nothing else!) finished. As soon as data is queried, the meta and data will be evicted from L1/L2 and populated to L3 . if it gets old, it will also be evicted from L3. Since metadata operations (in my environment) are more frequently used than data reads i hope to have a lot of often used metadata and additional data in L3 Cache.

Does FSAnalyze or Snapshot(Deletes) populate metadata to Caches?

If i delete a Directorytree with files do i populate this data into the caches or are caches cleared from deleted files? (i guess the first...)

Is a timecalculation based on experiences from another (comparable) cluster valid?

i.e.

Cluster 1 has 3Nodes and 1Million LINs. it needs 15 Minutes to evacuate Metadata and reformat the SSDs.

Cluster 2 has 3Nodes and 10Million LINs (based on last FSAnalyze). I calculate 2:30 hours for metadata evacuation and reformating of the SSDs

Thanks and Regards

--sluetze