What is the fastest and most reliable way to split a 50GB binary file into chunks of 5GB or less, and then reassemble it later?

Our servers are running Ubuntu Linux, and the binary file is a BSON dump of a large MongoDB collection. How reliable is a tool like split? Is there a faster or better way to do this?

4 Answers

split is very reliable. We use it for porting large log files, and it worked well for up to a couple of GBs ( not 50 gb anyway ).

I believe you can try using the split for your requirement, and let us know.

Split into 5GB files

split --bytes=5G inputfile

It will split into multiple files of 5GB and name it as xaa, xab, xac, .... and so on.

Concatenate

cat x* > outfile

by this you can concatenate as single file in the other end.

To split, split -b

To join, just cat.

AFAIK they are completely reliable, and I doubt there is something more efficient.

split & cat are totally reliable. You can additionally compress in-line like this. Suppose your input file is dump.bson:

gzip < dump.bson | split -b 32M - dump.bson.gz.

And then reconstitute with this:

cat dump.bson.gz.* | gunzip > dump.bson

Tip, this works just as well with xz(dec) in place of g(un)zip

If you have rar installed, it's worked very well for me:

To Separate

rar a -m0 -v5000m newfilename giantfile.foo

• a = add files to archive
• m0 = no compression
• v5000m = split into chunks of 5000 megabytes

To Reassemble:

unrar x newfilename.*

• x = extract

Benefits:

• CRC on the content of the split archive,
• split-file ordering kept automatically,
• multiple files and dirs can be included.