Hi all, 

I’m setting up bareos as a backup solution for my large (60TB) RAID. I’m 
backing up to another RAID on a different machine, and the File Daemon and 
Storage Daemon are connected by GbE. 

The setup works well. With no software compression, I’m maxing out the GbE 
link, sustaining 117 MB/s (10^6 *bytes/sec).  I’m looking into compression 
because 7.4Tb takes almost 18 hours to backup, and there will be more. With 
compression, I have a question: When Bareos reports “[FD|SD] Bytes Written”, is 
this is a post-compression value? (e.g., the number of bytes read by the FD is 
larger by the “Software Compression” percentage, correct?)

The short version is: assuming the above, it looks like my “effective backup 
rates” (Bytes read by the FD/sec) is:

No compression: 117Mb/sec (100%)
GZIP: 65.82 Mb/sec (56%)
LZOFAST: 236.44 Mb/sec (202%)
Pigz [1] projection: 532.76 Mb/sec (454%)

That last bit is a projection based on comparing the Parallel Implementation of 
GZip (PIGZ)[1] to the standard gzip on my system. I started messing with 
parallel compression because I noted that during a GZIP run, my 24-thread 
system was ~95% idle. It is interesting to note that PIGZ compiles against 
versions of libz found on RHEL/CentOS/SL 6 machines. 

I would like to submit a feature request for PIGZ support on Linux-based FDs, 
but I wanted to run it by the group first. It produces GZIP-compatible output 
files, it just does the compression in parallel if you have an SMP machine. (I 
checked by compressing with PIGZ and uncompressing with gunzip.)

Thanks,
Bryce

[1] http://zlib.net/pigz/

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,,,,Backup rate (1e6 Bytes/sec),,
Compression Method,Compression Ratio,SD Bytes Written,Time Elapsed (s),Compressed,Raw,Rate % non compressed
GZIP,91.0%,"20,690,583,231",3493,5.92,65.82,56%
LZOFAST,89.8%,"60,846,309,819",2523,24.12,236.44,202%
None,0%,"7,460,641,452,593",63599,117.31,117.31,100%
pigz projection,91.0%,"20,690,583,231",432,47.95,532.76,454%

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