Persistent data » History » Revision 5
Revision 4 (Greg Burri, 07/21/2009 01:33 PM) → Revision 5/18 (Greg Burri, 07/30/2009 04:29 PM)
h1. Structures
h2. Files cache
This file contains all the shared files and theirs SHA-1 hashes. This file is saved in user space after an update of the file list, it is completely loaded at the start of Aybabtu. If some paths of some files doesn't match the shared directory they are discarded.
You can see the proto file here : source:/protos/files_cache.proto
h3. Size
Here is a size approximation for 50'000 files stored in 1 TB. The overhead of the file format is not taken in account.
<pre>
Nb of files : 50'0000
Total size : 1 TB
Chunk Size : 32 MB
Average file per directory : 50
Average filename and dirname length : 50 char
Size of a hash : 20B
</pre>
<pre>
AverageFileSize = 1*1024^4 / 50'000 = 21MB
Sha1Size = floor(AverageFileSize / 32MB) * 20 * 50'000 = 1 * 20 * 50'000 = 977kB
FilenameSize = 50'000 * 50 * 2 = 4.8MB (2 bytes per char)
DirnameSize = (50'000 / 50) * 50 * 2 = 97kB
TotalSize = 977kB + 4.8MB + 97kB = 5.9MB
</pre>
h2. Configuration file
TODO..