---
title:  Disk Store Operation Logs
---

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At creation, each operation log is initialized at the disk store's `max-oplog-size`, with the size divided between the `crf` and `drf` files. When the oplog is closed, <%=vars.product_name_long%> shrinks the files to the space used in each file.

<a id="operation_logs__section_C0B1391492394A908577C29772902A42"></a>
After the oplog is closed, <%=vars.product_name%> also attempts to create a `krf` file, which contains the key names as well as the offset for the value within the `crf` file. Although this file is not required for startup, if it is available, it will improve startup performance by allowing <%=vars.product_name%> to load the entry values in the background after the entry keys are loaded.

When an operation log is full, <%=vars.product_name%> automatically closes it and creates a new log with the next sequence number. This is called *oplog rolling*. You can also request an oplog rolling through the API call `DiskStore.forceRoll`. You may want to do this immediately before compacting your disk stores, so the latest oplog is available for compaction.

**Note:**
Log compaction can change the names of the disk store files. File number sequencing is usually altered, with some existing logs removed or replaced by newer logs with higher numbering. <%=vars.product_name%> always starts a new log at a number higher than any existing number.

This example listing shows the logs in a system with only one disk directory specified for the store. The first log (`BACKUPCacheOverflow_1.crf` and `BACKUPCacheOverflow_1.drf`) has been closed and the system is writing to the second log.

``` pre
bash-2.05$ ls -tlra 
total 55180
drwxrwxr-x   7 person users        512 Mar 22 13:56 ..
-rw-rw-r--   1 person users          0 Mar 22 13:57 BACKUPCacheOverflow_2.drf
-rw-rw-r--   1 person users     426549 Mar 22 13:57 BACKUPCacheOverflow_2.crf
-rw-rw-r--   1 person users          0 Mar 22 13:57 BACKUPCacheOverflow_1.drf
-rw-rw-r--   1 person users     936558 Mar 22 13:57 BACKUPCacheOverflow_1.crf
-rw-rw-r--   1 person users       1924 Mar 22 13:57 BACKUPCacheOverflow.if
drwxrwxr-x   2 person users       2560 Mar 22 13:57 .
```

The system rotates through all available disk directories to write its logs. The next log is always started in a directory that has not reached its configured capacity, if one exists.

## <a id="operation_logs__section_8431984F4E6644D79292850CCA60E6E3" class="no-quick-link"></a>When Disk Store Oplogs Reach the Configured Disk Capacity

If no directory exists that is within its capacity limits, how <%=vars.product_name%> handles this depends on whether automatic compaction is enabled.

-   If auto-compaction is enabled, <%=vars.product_name%> creates a new oplog in one of the directories, going over the limit, and logs a warning that reports:

    ``` pre
    Even though the configured directory size limit has been exceeded a 
    new oplog will be created. The current limit is of XXX. The current 
    space used in the directory is YYY.
    ```

    **Note:**
    When auto-compaction is enabled, `dir-size` does not limit how much disk space is used. <%=vars.product_name%> will perform auto-compaction, which should free space, but the system may go over the configured disk limits.

-   If auto-compaction is disabled, <%=vars.product_name%> does not create a new oplog, operations in the regions attached to the disk store block, and <%=vars.product_name%> logs this error:

    ``` pre
    Disk is full and rolling is disabled. No space can be created
    ```