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hjmangalam/parsyncfp: follow-on to parsync (parallel rsync) with better startup perf

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Tags: SSH parallelism rsync github.com
Clipped on: 2020-04-06

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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)

See Changes at bottom.

The suspend/unsuspend bugs (there were actually 2) have been squashed (I think).


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.

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

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

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. If it detects that ssh keys are NOT set up correctly, it will ask for permission to try to remedy that situation. Check your local and remote ssh keys to make sure that it has done so correctly. Typically, they're in your ~/.ssh dir.

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 odd 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. There is a 'suspend.log' file in the ~/.parsyncfp dir that tracks these transitions.

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 tries 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 run at the same time, altho they will detect each others' fparts running and question this situation.

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.


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 gratuitous info to the screen and pause multiple times to allow checking of intermediate results.


[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] \
  • --trimpath|tp [s] +-- see "Options for using filelists" below
  • --trustme|tm /
  • --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

Options for using filelists

(thanks to Bill Abbott for the inspiration/guidance).

The following 3 options provide a means of explicitly naming the files you wish to transfer by means of filelists, whether by 'find' or other means. Typically, you will provide a list of files, for example generated by a DB lookup (GPFS or Robinhood) with full path names. If you use this list directly with rsync, it will remove the leading '/' but then place the file with that otherwise full path inside the target dir. So '/home/hjm/DL/hello.c' would be placed in '/target/home/hjm/DL/hello.c'.
If this result is OK, then simply use the '--fromlist' option to specify the file of files.

If the list of files are NOT fully qualified then you should make sure that the command is run from the correct dir so that the rsyncs can find the designated dirs & files.

If you want the file 'hello.c' to end up as '/target/DL/hello.c' (ie remove the original '/home/hjm'), you would use the --trimpath option as follows: '--trimpath=/home/hjm'. This will remove the given path before transferring it and assure that the file ends up in the right place. This should work even if the command is executed away from the directory where the files are rooted. If you have already modified the file list to remove the leading dir path, then of course you don't need to use '--trimpath' option.

  • --fromlist|fl [s] : take explicit input file list from given file, 1 path name per line.

  • --trimpath|tp [s] : path to trim from front of full path name if '--fromlist' file contains full path names and you want to trim them.

  • --trustme|tm : with '--fromlist' above allows the use of file lists of the form:

                      size in bytes<tab>/fully/qualified/filename/path  
                      825692            /home/hjm/nacs/hpc/movedata.txt
                      87456826          /home/hjm/Downloads/xme.tar.gz

This allows lists to be produced elsewhere to be fed directly to pfp without a file stat() or complete recursion of the dir tree. So if you're using an SQL DB to track your filesystem usage like Robinhood or a filesystem like GPFS that can emit such data, it can save some startup time on gigantic file trees.


Good Example 1

% parsyncfp  --maxload=5.5 --NP=4 \
--chunksize=\$((1024 * 1024 * 4)) \
--startdir='/home/hjm' dir[123]  \


  • "--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.
  • "--NP=4" forks 4 instances of rsync
  • "chunksize=$((1024 * 1024 * 4))" defines the chunksize as the product of numbers (equalling 4MB)
  • "--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

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

Good Example 2

--interface eth0  --chunksize=87682352 \
--rsyncopts="--exclude='[abc]*'"  nacs/fabio   


  • "--checkperiod 6" - defines a 6s cycle time between updates
  • "--NP 3" - requests 3 instances of rsync
  • "--interface eth0" - requests that the eth0 interface be monitored explicitly
  • "--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 --NP=8 --chunksize=500M --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 (M or m for Mega).

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\@moo.boo.yoo.com:/usr/local

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

### 1.6.3
- added check for underflow in fpart chunks; warning emitted if # of chunks is < # of rsyncs requested
- updated / replaced all 'route' and 'ifconfig' bits with 'ip' equivalents.  Also re-did the multihoming 
    bits to probe, and present all routed interfaces and IP #s so user can choose the right one on a multihomed
    host. Thanks to Ryan Novosielski for suggesting / pushing on this ;).
- usual bits of code cleanup and messup in equal amounts, tho overall things should progress more smoothly.
- detected a weird output format bug(?) inconsistency in CentOS 6.9 'ps' vs recent 'ps'.  Not going to fix.
  reveals itself if exceed MAXLOAD on CentOS 6.9 - the load balancing continues to work OK afaict but the suspended PIDs aren't shown correctly.  The workaround is to set MAXLOAD high enough that it won't be invoked.
- added more utilities to check for, before startup and corrected links to them.

### 1.6.1
- added total raw bytes transferred as well as autoscale to MB, GB, TB in signoff stanza.

### 1.60
- figured out why the suspend/unsuspends noted below weren't tracking correctly.  Thanks to Ben Dullnig 
for his perseverance and Mikael Barfred for his code suggestions. Lots of cosmetic and interface tweaks.  
Added Bill Abbott's suggestion to allow explicit sizing to the --fromlist option. Added a warning if the
number of chunkfiles exceed 2000 (hard-coded).  Also caught a rare condition where the run ends with suspended jobs. 
Now it should continue until the suspended PIDs get unsuspended and complete.

### 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.

### 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.

### 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.