HCoop / hcoop / debian / openafs.git / blame
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1 | =head1 NAME |
| 2 | ||
| 3 | fs_precache - Set precache size | |
| 4 | ||
| 5 | =head1 SYNOPSIS | |
| 6 | ||
| 7 | =for html | |
| 8 | <div class="synopsis"> | |
| 9 | ||
| 10 | B<fs precache> S<<< B<-blocks> <I<size in 1K blocks>> >>> | |
| 11 | [B<-help>] | |
| 12 | ||
| 13 | B<fs p> S<<< B<-b> <I<size in 1K blocks>> >>> | |
| 14 | [B<-h>] | |
| 15 | ||
| 16 | =for html | |
| 17 | </div> | |
| 18 | ||
| 19 | =head1 DESCRIPTION | |
| 20 | ||
| 21 | The B<fs precache> command configures to what degree the Cache Manager will | |
| 22 | attempt to prefetch cache blocks when an application opens a file for reading. | |
| 23 | If this behavior is enabled, whenever a file is opened for reading, the Cache | |
| 24 | Manager will immediately initiate an asynchronous fetch request for that file. | |
| 25 | This fetch request will fetch the configured amount of data for that file, and | |
| 26 | store the data in the cache. In some scenarios, this can improve performance. | |
| 27 | ||
| 28 | Note that this prefetching behavior is done by the Cache Manager itself. The | |
| 29 | underlying Operating System may also perform its own prefetching behavior, | |
| 30 | depending on various settings or application hints. | |
| 31 | ||
| 32 | This command was introduced in OpenAFS 1.5.37. | |
| 33 | ||
| 34 | =head1 OPTIONS | |
| 35 | ||
| 36 | =over 4 | |
| 37 | ||
| 38 | =item B<-blocks> <I<size in 1K blocks>> | |
| 39 | ||
| 40 | Specifies how much data to prefetch for each applicable file, in 1024-byte | |
| 41 | blocks. Specify 0 to disable prefetching behavior. By default, prefetching is | |
| 42 | disabled. | |
| 43 | ||
| 44 | =item B<-help> | |
| 45 | ||
| 46 | Prints the online help for this command. All other valid options are | |
| 47 | ignored. | |
| 48 | ||
| 49 | =back | |
| 50 | ||
| 51 | =head1 OUTPUT | |
| 52 | ||
| 53 | If the specified precache size has been set successfully, the following message | |
| 54 | will be printed: | |
| 55 | ||
| 56 | New precache size set. | |
| 57 | ||
| 58 | =head1 EXAMPLES | |
| 59 | ||
| 60 | The following command configures the Cache Manager to prefetch the first 100 | |
| 61 | kilobytes of any file that's opened for reading: | |
| 62 | ||
| 63 | % fs precache -blocks 100 | |
| 64 | New precache size set. | |
| 65 | ||
| 66 | =head1 PRIVILEGE REQUIRED | |
| 67 | ||
| 68 | The issuer must be logged in as the local superuser C<root>. | |
| 69 | ||
| 70 | =head1 SEE ALSO | |
| 71 | ||
| 72 | L<afsd(8)> | |
| 73 | ||
| 74 | =head1 COPYRIGHT | |
| 75 | ||
| 76 | Copyright 2013 Sine Nomine Associates | |
| 77 | ||
| 78 | This documentation is covered by the BSD License as written in the | |
| 79 | doc/LICENSE file. This man page was written by Andrew Deason for | |
| 80 | OpenAFS. |