I recently came across a few blade servers which, for whatever reason did not have their HP Smart Array controller configured for caching. These particular servers are HP StoreEasy blades with a Smart Array P220i controller.
I’ll quickly run through the steps carried out to configure the Smart Array cache.
Configuration
- I logged onto the server and launched the Smart Storage Administrator console
- We can see there are some status messages for the Smart Array P220i controller
- If we click on the ‘View all status messages’ link the popup below is displayed and informs us the cache is not configured
- Clicking the Configure link will give us some extra options
- Select the ‘Cache Manager’ menu and then click the ‘Cache Settings’ link
- Now we can configure the cache including the ratio of cache storage to be used for read and write requests
- Based on the IO pattern of these servers I decided to set a ratio of 70% for reads and 30% for writes. Obviously you should consider the needs of your environment before setting this option. Make sure to select the logical drive you wish to enable caching on – I only have one drive which is selected
- Having clicked the ‘OK’ button I am presented with a summary of the change, click ‘Finish’ to proceed
- We can see the alert no longer displays and the ‘Cache’ Status’ has change from ‘Not Configured’ to ‘OK’
I don’t expect to see a huge change to the performance of these servers as the logical drive is just the system disk – these blades actually use Cluster Shared Volumes (CSVs) for all the heavy work however it is always good to enable caching as it is beneficial. If you are enabling or modifying the cache settings for a storage controller remember to check the IO pattern your system works with. Some controllers will use their cache in an adaptive method – they will alter the ratio of read/write percentage on the fly to handle the workload.