Re: [BackupPC-devel] BackupPC 4.0.0alpha0 released

[<bac...@ko...>]

Craig Barratt wrote at about 21:08:30 -0700 on Sunday, June 23, 2013:
 > Also, you note a number of features that should significantly speed up
 > > backups (including rsync 30, c-code, --checksum flag, etc.). Have you
 > > done any benchmarking relative to v3.x?
 > 
 > 
 > It depends.  For slow clients, and initial backups (which involves a lot of
 > compression cpu time), there isn't much difference.  On faster clients I
 > have seen significant speed ups.  Other than initial compression, I suspect
 > the server load is significantly lower that 3.X, but I haven't made
 > measurements.
 > 
 > One place where 4.x is slower is that it doesn't implement block checksum
 > caching.  So if you go back to --ignore-times fulls, there is a lot more
 > work to do on the server compared to 3.X.  That case offsets some or all of
 > the other performance gains.  I haven't decided whether it is worth
 > implementing block checksum caching because --checksum is quite convenient.
 > 
 > Here are two examples using --checksum fulls:
 > 
 >  - A fast client (MacbookPro with a flash drive): a full is about 3x
 > faster, an incremental is about 4x faster.  An initial backup with an empty
 > pool is no faster.  An initial backup with a populated pool is maybe 30%
 > faster (since --checksum allows any pool file to be matched), with a big
 > saving in network traffic.  The reported BackupPC speed is >100MB/sec for
 > the full (but obviously not much data is being transferred because of
 > --checksum).
 > 
 >  - Backing up part of my BackupPC server to the same server (an old Xeon
 > with 3ware RAID): a full is about 30% faster, an incremental is about 3x
 > faster (another backup was running during these tests).
 > 

How does memory usage compare?
I am asking because I have made good use running BackupPC on various
plugcomputers and NAS devices that have limited memory and CPU
power. From the above, it would seem that in general CPU performance
should be the same or better (depending on the scenario). So, I am now
wondering about memory requirements...