Configuration parameters for AFM

Indicates the time at which the requests start flushing to the home cluster. For write-intensive applications that write to the same set of files, this delay is helpful because it replaces multiple writes to the home cluster with a single write containing the latest data. However, setting a very high value weakens the consistency of the data on the remote cluster.

Defines the frequency of revalidation triggered by a look-up operation such as ls or stat on a directory from the cache cluster. AFM sends a message to the home cluster to find out whether the metadata of that directory is modified since it was last revalidated. If so, the latest metadata information at the home cluster is reflected on the cache cluster.

Defines the frequency of revalidations triggered by the read and update operations on a directory from the cache cluster. AFM sends a message to the home cluster to find whether the metadata of that directory is modified since it was last revalidated.

Open requests on files or sub-directories on that directory are served from the cache fileset until the afmDirOpenRefreshInterval expires, after which the open requests are sent to the home cluster.

Defines the interval until which the MDS waits after it detects that the home cluster is inaccessible before declaring the outage by moving the cache cluster state to Disconnected.

If enabled at cache, exported paths from home with kerberos-enabled security levels like sys, krb5, krb5i, krb5p are mounted at cache in the increasing order of security level - sys, krb5, krb5i, krb5p. For example, the security level of exported path is krb5i then at cache, AFM tries to mount with level sys, followed by krb5, and finally mounts with the security level krb5i. If disabled at cache, exported paths from home are mounted with security level sys at cache. You must configure KDC clients on all the gateway nodes at cache before enabling this parameter.

Is used with afmDisconnectTimeout to control the duration of a network outage between the cache and home clusters before the data in the cache expires and becomes unavailable until a home reconnection occurs.

Defines the frequency of revalidation triggered by a look-up operation on a file such as ls or stat, from the cache cluster. AFM sends a message to the home cluster to determine that the metadata of the file is modified since it was last revalidated. If so, the latest metadata information at home is reflected on the cache cluster.

Defines the frequency of revalidations triggered by the read and write operations on a file from the cache cluster. AFM sends a message to the home cluster to determine that the metadata of the file is modified since it was last revalidated.

Open requests on the file are served from the cache fileset until the afmFileOpenRefreshInterval expires, after which the open requests are sent to the home cluster.

Indicates if automatic eviction is triggered on a fileset.

Controls the visibility of the home snapshot directory in the cache cluster. For this to be visible in the cache cluster, this variable must to be set to yes, and the snapshot directory name in the cache and home clusters must not be the same.

When a sparse file at the home cluster is read into the cache, the cache cluster maintains the sparseness, if the size of the file exceeds the afmReadSparseThreshold. If the size of a file is less than the threshold, sparseness is not maintained at the cache cluster.

Specifies the gateway node hashing algorithm that minimizes the impact of gateway nodes joining or leaving the active cluster by running as few recoveries as possible and balance mapping of AFM filesets across the gateway node. Valid values are 1,2,4, and 5. Default value is 2. You can specify the value by using mmchconfig. For example, to set the value 4, run mmchconfig afmHashVersion=4.

Specifies the number of filesets in the cluster on all file systems, on which recovery is run.

Specifies the interval after which the primary gateway retries an operation at home, in cases where home is in an unhealthy state (see Unmounted, Dropped states). Needs the GW node recycle or -i option for immediate effect.

Specifies the time that AFM waits for completion of any inflight asynchronous operation which is synchronizing with the home cluster. Subsequently, AFM cancels the operation and synchronizes again after home is available.

Specifies the time that AFM waits for completion of any inflight synchronous operation which is synchronizing with the home cluster. When any application is performing any synchronous operation at cache, AFM tries to get a response from home. If home is not responding, application might be unresponsive. If operation does not complete in this timeout interval, AFM cancels the operation.

Specifies the time that AFM waits for completion of revalidation to get response from the home cluster. Revalidation checks if any changes are available at home (data and metadata) that need to be updated to the cache cluster. Revalidation is performed when application trigger operations like lookup or open at cache. If revalidation is not completed within this time, AFM cancels the operation and returns data available at cache to the application.

Cache data refresh operation in asynchronous mode improves performance of applications querying data. Specify the value as 'yes' for the cache data refresh operation to be in asynchronous mode. In IW mode, revalidation request for files or directories is queued as an asynchronous request, and data in the last synchronized state is returned. The data is refreshed at cache after revalidation with home is complete. Revalidation time depends on the network availability and its bandwidth.