# Backend I/O metrics
<a name="backend-io-metrics"></a>

The following metrics report information on read and write operations between the cache and its linked data repository. The metric takes one dimension (`FileCacheId`) and is published into the `AWS/FSx` namespace in CloudWatch.


| Metric | Description | 
| --- | --- | 
| `RepositoryReadSuccess` | The rates of files being read into the cache from its linked data repository. | 
| `RepositoryReadFailure` | The rate of files failing to be read into the cache from its linked data repositories.<br />If you observe a high rate of read failures, check if any data repository association (DRA) is unreachable or misconfigured, and if the link between your VPC and an on-premises data store is saturated. If the link is not saturated, you can create a larger cache. | 
| `RepositoryWriteSuccess` | The rate of files being written from the cache to its linked data repositories. | 
| `RepositoryMetadataReadSuccess` | Understand the rate at which the workload is triggering the loading of file and directory metadata into the cache. | 
| `RepositoryMetadataReadFail` | The rate of file and directory metadata failing to be read into the cache from its linked data repositories.<br />If you have high metadata read failures, check the connectivity to the linked data repository and share the workload. | 
| `RepositoryMetadataReadNotFound` | The rate at which cache is looking up the data repository for paths that don't exist. | 
| `RepositoryOperationsInProgress` | The number of read and write operations (including metadata operations) on data repositories that are in progress. |