By adding SSD’s to any cluster, Global Namespace Acceleration (GNA) for the whole cluster can be achieved. The acceleration is important for workflows that do a lot of metadata calls like lookups.   A primary example would be for user home directories, especially where the users are coming in largely from Windows or Mac clients. With Windows or the Mac finder, when you open a folder you will sometimes see the flashlight icon spinning. What it is doing is touching all of the entries in that folder to create the icons to display. These are all metadata calls. With SSD, the flashlight will spin for far less time if at all since the lookups come out of the SSD.   Another workflow that benefits would be a directory that is created by a program and has huge numbers of files. Even a UNIX ‘LS’ command will take a long time to return since it has to do a metadata lookup on every file on disk. With SSD it is far faster. There are many other examples.   With Global Namespace Acceleration (GNA), this benefit is applied to all the data in the pools GNA is turned on for. Remember you can have Metadata Acceleration in any given pool just by adding SSD's to that pool (all the SmartPools rules apply) or you can have GNA which means you are extending the SSD benefits to pools without SSD's. To achieve GNA, you need at least 20% of the nodes with SSD's and at least 2% of the total cluster capacity must be from SSD's.
What are the benefits of adding SSD's to a cluster and what type of workflows will benefit from them?
SSD's and GNA benefits in Isilon.