Watermarks are optional parameters for several tools. The purpose of watermarks is to avoid disk overload or running out of space on a single partition. An alternative benefit of watermarks, is that the Delete tool (or other tools like Relocation) will begin the moment disk space reaches capacity.
- To avoid running out of space - use High Watermark
- To avoid the unnecessary deleting data - use Low Watermark
- To fill one disk first, then another - use different Priority
- To spread disk usage - use same Priority value, same Balance
- To spread disk usage but not equally - same Priority, different balance
Watermarks are typically used during installation when many physical HDDs are mounted to a filesystem which Call Recording tools may use for storage. If we want to fill these discs with equally we may use watermarks.
Preconditions:
All paths which will be used in the watermarks settings must be accessible for tools. This means that they have to be mounted and visible to the user.
Parameters:
| Additional paths | This is the absolute path which defines the directory where disk quota is measured. In several tools this may also affect files which will be processed, meaning that only files which are in that specific directory or subdirectories will be archived, deleted and so on. |
| Priority | The lower the priority number is, the earlier it will be filled. This means that if there are many drives, then the first one used will be that with the lowest number, once it has been filled, the second lowest number of priority will be used... |
| Balance | If there are many paths with the same Priority, Balance comes to play. Balance is a positive number which indicates the percentage of data that will be stored on this path. For a better understanding. we recommend using numbers which in the sum of all paths will amount to 100 - then it’s similar to the percentage. If there are 3 drives with a balance of 20, 30, 50, then every time we choose a path we will chose with the probability of 50% the balance 50 drive, with 30% probability the 30 balance and with 20% probability the 20 balance drive. In the best case scenario, if we write down 10 files, there will be 2 on the 20 balance drive, 3 on the 30 balance drive and 5 on the 50 balance drive. BUT all of them must have the SAME PRIORITY |
| Low Watermark (MB) | This path is considered suitable if a certain partition uses MORE than the lowest watermark. This is used for tools such as Delete (which REMOVE data). This tool starts to delete data when there is more space used than the lowest watermark. For a 10GB partition, if the lowest watermark is 2GB, but only 1GB is used, then this path is not usable and will be skipped. Once it is filled and there are 3GB used, the Delete tool will start deleting. |
| High Watermark (MB) | This partition is considered suitable if there is LESS space used than the highest high watermark. It is used for tools such as Synchro (which ADD data). This tool will add data to this partition until the highest watermark is reached. For a 10GB partition, if 8 GB is the high watermark, then when 7GB are used we will still add data, but once it reaches a usage of 8GB and some MB this partition won't be used by this tool. |
Please note that FREE / USED space is space which has Java Virtual Machine on that partition. There may be different disk quotas for different linux users.
The process of choosing a path is completed after a BATCH of couples is processed. This means that after the Synchro tool synchronizes the amount of calls set as "Calls to process in one period", a new path is chosen and thus the exact result cannot be anticipated.
Balance uses a random algorithm which determines the target path even after the BATCH of couples is processed. The higher the number of calls that are processed, the more precisely the couples are spread across partitions according to balance. After an estimated 100,000 processed couples, the balance of used partitions should be as expected.
The administrator or user who sets up the Watermark must know size of the partition which is usable by MLM.
Partition usage does not count only media, but all content on the partition!