Sean M Clark wrote:
> Carlo Filippetto wrote:
>   
>> Hi,
>> I would like to know if is true that I have so slow troughput as this:
>>     
> [...]
>   
>> FULL
>> -----
>>   Elapsed time:           1 day 22 hours 13 mins 37 secs
>>     
> [...]
>   
>>   Rate:                   371.7 KB/s
>>   Software Compression:   15.5 %
>>
>>     
> [...]
>   
>> All my jobs have the maximum compression
>>
>> /    Options {
>>         compression = GZIP9 #aggiungo compressione massima
>>
>>
>> /P.S. is this the maximum compression??
>>     
> I saw someone else mentioned this already, but yes, GZIP9 is the
> maximum, and that might actually be WHY the rate is slow.
> The higher you set the compression rate, the more time the program
> spends trying to cram more data into each packet before sending it.
> If the compression rate is high enough, it may actually take much
> more time to do the compression than is saved by sending less data.
>
>   
I can attest to this, GZIP compression (especially at GZIP9) can make a 
large difference in backup transfer speeds, especially when combined 
with client data encryption.  I wouldn't be surprised if he was to get 
5-10MB/sec after disabling GZIP compression, especially if the client 
does not have modern hardware.
> Unless space on the backup media or bandwidth usage are the biggest
> concerns, I tend to drop the compression all the way down to
> GZIP1-GZIP4, or turn it off altogether.
>   
This is very true.  There is often very little gain in compression ratio 
with levels greater than GZIP1 or GZIP2, while higher levels will use 
considerably more CPU time.  Of course this depends entirely on the data 
you are compressing, so he should try the various levels himself to see 
whether there is any advantage to using a level greater than GZIP1.
> ( I'm hoping to someday see "LZMA1-LZMA9" or "XZ1-XZ9" compression
> options, too... )
>
>   
Ditto.


-Steve


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