zfs issue - disappearing data

[Jeremy Chadwick]

On Fri, May 03, 2013 at 10:43:21AM -0700, Mike Carlson wrote:
> {snipping parts I have no knowledge of}
> 
>    History for 'data':
> {snip}
>    2013-02-25.17:12:22 zfs set compression=lzjb data
> 
> We had a file structure drop off:
> 
> /data/XML_WORKFLOW/XML_ORDERS/
> 
> around 5/2/2012 @ 17:00
> 
> In that directory, there were a few thousand directories (containing
> images and a couple metadata text/xml files)
> 
> What is odd, is doing a du -h in the parent XML_WORKFLOW directory,
> only reports ~150MB:
> 
>      # find . -type f |wc -l
>    86
>    # du -sh .
>    130M .
> 
> 
> however, df reports 1.5GB:
> 
>    # df -h .
>    Filesystem Size Used Avail Capacity Mounted on
>    data/XML_WORKFLOW 28T 1.5G 28T 0% /data/XML_WORKFLOW

This is one of the side effects of ZFS compression.  Google "zfs
compression df du freebsd".  You'll find lots of chat about this.  To be
clear: it is not a FreeBSD-specific thing.

You may also find the -A flag to du(1) useful.

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Mountain View, CA, US                                            |
| Making life hard for others since 1977.             PGP 4BD6C0CB |