L3 cache on archive-class node pools

Some Isilon nodes are high-capacity units designed primarily for archival work flows, which involve a higher percentage of data writes compared to data reads. On node pools made up of these archive-class nodes, SSDs are deployed for L3 cache, which significantly improves the speed of file system traversal activities such as directory lookup.

L3 cache with metadata only stored in SSDs provides the best performance for archiving data on these high-capacity nodes. L3 cache is on by default, as described in the following table.

Nodes
Comments
NL-series
For node pools made up of NL-series nodes with hard-disk drives (HDD) smaller than 4 TB in capacity, L3 cache stores both data and metadata in SSDs by default. You can turn off L3 cache on NL-series nodes with 4 TB or smaller HDDs. However, we recommend that you leave L3 cache enabled, as NL-series node pools typically do not have large numbers of SSDs. From a performance perspective, the benefits of L3 cache outweigh the benefits of using SSDs as storage drives on these node pools.

For node pools made up of NL-series nodes with HDDs greater than 4 TB in capacity, L3 cache stores metadata only in SSDs and cannot be disabled.

HD-series
For all node pools made up of HD-series nodes, L3 cache stores metadata only in SSDs and cannot be disabled.
Infinity A-series
For all node pools made up of Infinity A-series nodes, L3 cache stores metadata only in SSDs and cannot be disabled.