Customizing PC-CacheFS

You can customize PC-CacheFS to make your cache perform according to your needs by changing advanced settings. You can change settings for each drive, or configure settings that apply to all drives available to be cached. Use PC-CacheFS advanced settings to configure the following properties:

• Directory Caching - Caches the attributes of a directory.

• Directory Time-out - Determines how long PC-CacheFS will retain a cached copy of directory information.

• File Time-out - Determines how often PC-CacheFS compares the modification time of the file on the source drive with the cached copy.

• Read Size - The number of bytes of information used during a read function.

• Write Size - The number of bytes of information used during a write function.

Directory Caching

PC-CacheFS provides the ability to move information about characteristics of and changes to directory structures in your cache. Moving this information into the cache saves the time it takes to search for directory information on your server.

Directory Time-out

The directory time-out determines how long PC-CacheFS will retain a copy of the directory information. The minimum and maximum time-out values establish a range. (The default range is between a 30-second directory time-out minimum and a 120-second maximum.) PC-CacheFS selects a value within the range based on the amount of time that has passed since the directory was last modified. Recently modified directories are read again more quickly than less-recently modified directories.

If a file is copied to the source drive from a computer other than yours, you will not see the changes until the time-out expires and PC-CacheFS updates the cache. Setting low time-out values increases directory consistency at the expense of network traffic. Use higher time-out values for directories that are modified only from your computer, or if you are accessing information using a slow network connection, such as a PPP dial-up connection.

File Time-out

The file time-out determines how often PC-CacheFS compares the modification time of the file on the source drive with the cached copy. The minimum and maximum time-out values establish a range. (The default range is between a 3-second minimum and a 60-second maximum.) PC-CacheFS selects a value within the range based on the amount of time that has passed since the file was modified. Recently modified files are checked for consistency more frequently than less-recently modified files.

Setting low time-out values increases file consistency at the expense of network traffic. Use higher time-out values for files that change infrequently or if you are accessing information using a slow network connection, such as a PPP dial-up connection.

If the file on the source drive changes infrequently, you can increase the file time-out to allow more time to pass between consistency checks. For example, you can increase the default file time-out maximum from 60 seconds to 75 seconds, and increase the minimum from 3 seconds to 5 seconds. An amount of time greater than 5 seconds but not more than 75 seconds will pass before PC-CacheFS makes a consistency check of the cache and the source drive. The additional time between consistency checks results in less network traffic and improved network performance.

If the file on the source drive changes frequently, you can ensure greater consistency between the file on the source drive and the copy in your cache by decreasing the default file time-out maximum from 60 seconds to 45 seconds and minimum from 3 seconds to 2 seconds. An amount of time greater than 2 seconds but not more than 45 seconds will pass before PC-CacheFS makes a file comparison between the source drive and your cache. Because comparisons and updates of cache and server information are more frequent, greater load is added to your network and you may notice more of a delay in retrieving information. In most situations, you do not need to decrease the file time-out minimum below the 3-second default.

Read or Write Size

The read size is the number of bytes of information used during a read function. A read function is any task that retrieves information from a file, such as opening a file for editing. In the PC-CacheFS Monitor, the effects of the read function are displayed in the field, Total Kbytes Read From Cache And Source Drives.

The write size is the number of bytes of information used during a write function. A write function is any task that causes information in your cache to be changed, such as saving a file, deleting a file, or renaming a file. The effects of the write function are displayed in the field, Modifications Made To Source Drives (Writes, Deletes, Renames).

PC-CacheFS breaks down large read and write requests into smaller blocks of the specified read or write size to help your computer perform other tasks in a timely manner. You can select a read or write size from 512 to 8192 bytes.

The default value of 8192 bytes is suitable for most LAN connections. Selecting a smaller read or write size may provide improved response times when accessing information using a slow network connection, such as a PPP dial-up connection.

To Change Advanced Settings

1. In the PC-CacheFS Monitor, click Cache, and then click Configuration.

   The PC-CacheFS Configuration dialog box opens.

2. Click Let Me Specify My Own Cache Settings.

3. Click the Advanced button.

4. In the PC-CacheFS Advanced Configuration dialog box:

   1. To configure a single drive, click Configure Drives Independently, then click the tab showing the drive letter of the drive for which you want to change settings.

   2. To configure options for all drives, click Use One Setting For All Drives.

5. Change the required settings, and then click OK.