![]() |
![]() |
To ensure that free space is available on your local file systems, the HSM client monitors space usage and automatically migrates files whenever it is necessary. Files are prioritized for automatic migration based on the number of days since they were last accessed, their size, and the age and size factors that you set for your file system.
The HSM client provides two types of automatic migration: threshold migration and demand migration. Threshold migration maintains a specific level of free space on your local file system. The space monitor daemon checks space usage on your local file systems at intervals that you specify. When space usage reaches the high threshold that you set for a file system, migration automatically sends eligible files to storage. When space usage reaches the low threshold that you set for a file system, migration stops. For example, if you set the high threshold for your file system to 80 percent and the low threshold to 70 percent, files begin migrating to storage when there is less than 20 percent of available space on your local file system. Files stop migrating when there is more than 30 percent of available space on your local file system.
Demand migration responds to an out-of-space condition on your local file system. The space monitor daemon checks for an out-of-space condition every ten seconds. Threshold migration starts automatically if your file system runs out of space. As files migrate, space becomes available on your file system, and the process that caused the out-of-space condition continues without waiting for threshold migration to complete. You do not receive an out-of-space error message. For example, if you attempt to copy a very large file into your file system, and there is not enough available space for the file, eligible files begin migrating automatically from your local file system to storage. As space becomes available, the process continues to copy the file to your file system.