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Persistent data » History » Revision 4

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Greg Burri, 07/21/2009 01:33 PM


Structures

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.

You can see the proto file here : source:/protos/files_cache.proto

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.

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
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

Configuration file

TODO..

Updated by Greg Burri over 15 years ago · 4 revisions