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What version of Perl is required? · Issue #22 · hjmangalam/parsyncfp

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Tags: parallelism rsync
Clipped on: 2019-06-04

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follow-on to parsync (parallel rsync) with better startup perf
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a parallel rsync wrapper in Perl. Released under GPL v3.

(Version changes moved to the bottom of this file)

IMPORTANT NOTE (May 31, 2019)

Thanks to the long-suffering efforts of Jeff Dullnig, I've discovered that when parsyncfp goes thru multiple suspend/unsuspend cycles, it fails to correctly rsync all the src files to the target.

If the '--maxload' option is kept high enough to avoid any suspensions, it syncs correctly.

If you're using parsyncfp now, please be aware that if forked rsyncs cycle thru suspend / unsuspends you will probably not end up with a correct target. I'll be working on this to determine if it can be fixed or if that 'feature' has to be removed.


parsyncfp (pfp) is the offspring of my parsync (more info here) and Ganael LaPlanche's fpart, which collects files based on size or number into chunkfiles which can be fed to rsync on a chunk by chunk basis. This allows pfp to begin transferring files before the complete recursive descent of the source dir is complete. This feature can save many hours of prep time on very large dir trees.

parsyncfp requires 'perfquery' and 'ibstat', Infiniband utilities both written by Hal Rosenstock < hal.rosenstock [at] > if your use involves transit over IB networks.

pfp is primarily tested on Linux, but is being ported to MacOSX as well.

pfp needs to be installed only on the SOURCE end of the transfer and only works in local SOURCE -> remote TARGET mode (it won't allow remote local SOURCE <- remote TARGET, emitting an error and exiting if attempted). It requires that ssh shared keys be set up prior to operation see here.

It uses whatever rsync is available on the TARGET. It uses a number of Linux-specific utilities so if you're transferring between Linux and a FreeBSD host, install parsyncfp on the Linux side.

The only native rsync options that pfp uses is '-a' (archive) & '-s' (respect bizarro characters in filenames). If you need to define the rsync options differently, then it's up to you to define ALL of them via '--rsyncopts' (the default '-a -s' flags will NOT be provided automatically.

pfp checks to see if the current system load is too heavy and tries to throttle the rsyncs during the run by monitoring and suspending / continuing them as needed.

It appropriates rsync's bandwidth throttle mechanism, using '--maxbw' as a passthru to rsync's 'bwlimit' option, but divides it by NP so as to keep the total bw the same as the stated limit. It monitors and shows network bandwidth, but can't change the bw allocation mid-job. It can only suspend rsyncs until the load decreases below the cutoff. (If you suspend parsyncfp (^Z), all rsync children will suspend as well, regardless of current state.)

Unless changed by '--interface', it tried to figure out how to set the interface to monitor. The transfer will use whatever interface routing provides, normally set by the name of the target. It can also be used for non-host-based transfers (between mounted filesystems) but the network bandwidth continues to be (usually pointlessly) shown.

NB: Between mounted filesystems, parsyncfp sometimes works very poorly for reasons still mysterious. In such cases (monitor with 'ifstat'), use 'cp' or tnc for the initial data movement and a single rsync to finalize. I believe the multiple rsync chatter is interfering with the transfer.

It only works on dirs and files that originate from the current dir (or specified via "--startdir"). You cannot include dirs and files from discontinuous or higher-level dirs.

the ~/.parsyncfp files

The cache dir (~/.parsyncfp by default) contains the fpcache dir which holds the fpart log and all the PID files as well as the chunk files (f*). parsyncfp no longer provides cache reuse because the fpart chunking is so fast. The log files are datestamped and are NOT overwritten. A new option allows you to specify alternative locations for the cache as well as specifying locations for multiple instances so that many parsyncfps can co-exist at the same time.

Odd characters in names

parsyncfp will sometimes refuse to transfer some oddly named files, altho recent versions of rsync allow the '-s' flag (now a parsyncfp default) which tries to respect names with spaces and properly escaped shell characters. Filenames with embedded newlines, DOS EOLs, and other odd chars will be recorded in the log files in the ~/.parsyncfp dir.

** Debugging ** To see where you (or I) have gone wrong, look at the rsync-logfile* logs in the .parsyncfp dir. If you're a masochist, use the '--debug' flag which will spew lots of grotacious gratuitous info to the screen.


[i] = integer number
[f] = floating point number
[s] = "quoted string"
( ) = the default if any
The syntax 'longarg|shortarg' means that either the long or short form may be used to denote that option.

  • --NP|np [i] (sqrt(#CPUs)) : number of rsync processes to start optimal NP depends on many vars. Try the default and incr as needed
  • --altcache|ac (~/.parsyncfp) : alternative cache dir for placing it on a another FS or for running multiple parsyncfps simultaneously
  • --startdir|sd [s] (pwd) : the directory it starts at(*)
  • --maxbw [i] (unlimited) : in KB/s max bandwidth to use (--bwlimit passthru to rsync). maxbw is the total BW to be used, NOT per rsync.
  • --maxload|ml [f] (NP+2) : max system load - if sysload > maxload, an rsync proc will sleep for 10s
  • --chunksize|cs [s] (10G) : aggregate size of files allocated to one rsync process. Can specify in 'human' terms [100M, 50K, 1T] as well as integer bytes.
  • --rsyncopts|ro [s] : options passed to rsync as quoted string (CAREFUL!) this opt triggers a pause before executing to verify the command(+)
  • --fromlist|fl [s] ........... take explicit input file list from given file, 1 fully qualified path name per line.
  • --interface|i [s] : network interface to monitor (not use; see above)
  • --checkperiod|cp [i] (5) : sets the period in seconds between updates
  • --verbose|v [0-3] (2) : sets chattiness. 3=debug; 2=normal; 1=less; 0=none. This only affects verbosity post-start; warning & error messages will still be printed.
  • --dispose|d [s] (l) : what to do with the cache files. (l)eave untouched, (c)ompress to a tarball, (d)elete.
  • --email [s] : email address to send completion message
  • --nowait : for scripting, sleep for a few s instead of pausing
  • --version : dumps version string and exits
  • --help : this help


Good Example 1

% parsyncfp  --maxload=5.5 --NP=4 --startdir='/home/hjm' dir1 dir2 dir3 hjm@remotehost:~/backups


  • "--startdir='/home/hjm'" sets the working dir of this operation to '/home/hjm' and dir1 dir2 dir3 are subdirs from '/home/hjm'
  • the target "hjm@remotehost:~/backups" is the same target rsync would use
  • "--NP=4" forks 4 instances of rsync
  • "--maxload=5.5" will start suspending rsync instances when the 5m system load gets to 5.5 and then unsuspending them when it goes below it.

It uses 4 instances to rsync dir1 dir2 dir3 to hjm@remotehost:~/backups

Good Example 2

parsyncfp   --checkperiod 6  --NP 3 --interface eth0  --chunksize=87682352 
   --rsyncopts="--exclude='[abc]*'"  nacs/fabio   hjm@moo:~/backups


  • --chunksize=87682352 - shows that the chunksize option can be used with explicit integers as well as the human specifiers (TGMK).

  • --rsyncopts="--exclude='[abc]*'" - shows the correct form for excluding files based on regexes (note the quoting)

  • nacs/fabio - shows that you can specify subdirs as well as top-level dirs (as long as the shell is positioned in the dir above, or has been specified via '--startdir'

Good Example 3

parsyncfp -v 1 --nowait --ac pfpcache1 --NP 4 --cp=5 --cs=50M --ro '-az'  
linux-4.8.4 moo:~/test


  • short version of several options (-v for --verbose, --cp for checkperiod, etc)
  • shows use of --altcache (--ac pfpcache1), writing to relative dir pfpcache1
  • again shows use of --rsyncopts (--ro '-az') indicating 'archive' & compression'.
  • includes '--nowait' to allow unattended scripting of parsyncfp

Good example 4

parsyncfp-list --NP=8 --chunksize=500k --fromlist=/home/hjm/dl550


  • if you use the '--fromlist' option, you cannot use explicit source dirs (all the files come from the file of files (which require full path names)
  • that the '--chunksize' format can use human abbreviations (k or K for kilo).

Error Example 1

% pwd
/home/hjm  # executing parsyncfp from here

% parsyncfp --NP4 --compress /usr/local  /media/backupdisk

Why this is an error:

  • '--NP4' is not an option (parsyncfp will say "Unknown option: np4") It should be '--NP=4'
  • if you were trying to rsync '/usr/local' to '/media/backupdisk', it will fail since there is no /home/hjm/usr/local dir to use as a source. This will be shown in the log files in ~/.parsyncfp/rsync-logfile-_# as a spew of "No such file or directory (2)" errors
  • the '--compress' is a native rsync option, not a native parsyncfp option. You have to pass it to rsync with "--rsyncopts='--compress'"

The correct version of the above command is:

% parsyncfp --NP=4 --rsyncopts='--compress' --startdir=/usr local /media/backupdisk

Error Example 2

% parsyncfp --start-dir /home/hjm mooslocal hjm\

Why this is an error:

  • this command is trying to PULL data from a remote SOURCE to a local TARGET. parsyncfp doesn't support that kind of operation yet.

The correct version of the above command is:

% parsyncfp  --startdir=/usr  local  hjm\@remote:/home/hjm/mooslocal```

## Changes

### 1.58
- added '--fromlist' to allow explicit lists of files to be pfp'ed.  Suggested by 
Bill Abbott to support GPFS's mmapplypolicy to generate lists so that pfp can immediately 
start moving data instead of iterating thru miles of already-synced files. Thanks, Bill.

### 1.57 
- added explicit GPL v3 licence 

### 1.56
- added a better measurement of TCP bytes sent (via /proc/net/dev) 
- added attempt at measuring RDMA bytes sent by using 'perfquery'; looks like it's
doing what it's supposed to.

### 1.54
- Bungled a commit.  This one should straighten is out.

### 1.53 
- removed internal space handling for target names since this interferes with multiple
dir targets.  Have to re-think this.

### 1.50
- fixed Ken Bass' bug where trimming dir name was not constrained to front
   of the string and could lead to problems if dir was names something like
   if the leading name was '/data/' the condensed, trimmed dir was 
   changed to
   'rna/hjm/rnaseq/something/version/smith' ie removal of ALL 'data/'
- fixed finding top level targets with embedded spaces - had to trim spaces
   and escape filenames going into fpart.
- many verbosity fixes
- some changes to ending text to reference both rsync and fpart logs 

### 1.47
- changed format of output to add elapsed time, changed date format
- code cleanup
- fixed bandwidth speed calculation
- updated help and fixed some inaccuracies for latest version.
- added (declinable) scripted mod to ~/.ssh/config to reduce ssh warnings

### 1.46
- made it variably verbose (--verbose)
- adjusted ending conditions to be accurate
- some code cleanup.  getting there.
- added checks for multihomed devices.

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