PRIMECLUSTER Global File Services Configuration and Administration Guide 4.1 (Linux)

4.2.1 Effects of file system operation and system load

To maintain strict file system consistency, the GFS Shared File System processing sometimes significantly slows down during the following operations:

• When frequently creating or deleting files and directories in the same directory from multiple nodes, and repeatedly monitoring the modification of such a directory with readdir(2), stat(2), and so on.
• When frequently updating the same block in the same file from multiple nodes.
• When frequently referencing from other nodes a file that is frequently updated from one or more nodes.
• When ls(1) with the -l option or such a command as cp(1), du(1) and tar(1) requiring the attributes of files under the directory is executed when one directory contains 10,000 or more files.

In the above cases, file system throughput may improve by changing the monitoring or access frequency or by dividing a target file.

CPU and I/O loads may be concentrated on the node where the MDS managing the file system meta-data. This can happen when such operations as file creation, deletion, and extension that cause the modification of the file system meta-data are frequently done. In such a case, file system throughput may be improved by increasing CPU throughput of the node where the MDS operates.