sounds like dumb question but there are no ready answers at SF
can the cache pool have different name than the zpool?
eg: suppose there is a zpool "tank" serving NFS and iSCSI
can a new cache pool be added as "xyz1" for it to be serving the "tank"?
or is there a per pool cache concept?
Best Answer
First of all, for general ZFS best practices the Solaris Internals wiki is quite useful: http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide
If you want, you can create a separate ZFS pool composed entirely of SSDs. However, this will not improve the performance of any other pools. A more cost-effective approach for most workloads is to use the hybrid storage pool feature; that is, adding SSDs to normal spinning disk in order to improve read and/or write performance.
Key points:
SSDs can be added in to an existing pool to improve the performance of that pool only. They don't have different names - they are just devices within the pool. You can add multiple cache and log devices to the pool depending on your performance requirements.
To improve the read performance of the pool, assign SSDs as cache devices ("L2ARC").
To improve the write performance of the pool, assign SSDs as log devices ("ZIL").
The L2ARC is a read cache that fills up over time and stores data based on a combination of which blocks are most frequently used and most recently used. This provides fast access to "hot" data. It gives almost the speed benefit of RAM at a lower cost per gigabyte.
The ZIL is an intent-log - adding SSDs allows synchronous writes to happen at high IOPS and very low latency, which improves application performance in some cases (e.g. databases and NFS shares).