zfs issue - disappearing data

[Mike Carlson]

On 5/3/2013 11:36 AM, Jeremy Chadwick wrote:
> 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.
>

Hey Jeremy, thanks for the reply!

I thought of that, and the discrepency is too much.

du -Ah :

    # du -Ah
      16k    ./XML_PRINTABLE/MC0012404
    1.5k    ./XML_PRINTABLE/7172142/thumbnails
      14k    ./XML_PRINTABLE/7172142
      13k    ./XML_PRINTABLE/MC0012410
      11k    ./XML_PRINTABLE/MC0012403
      13k    ./XML_PRINTABLE/MC0012409
    2.5k    ./XML_PRINTABLE/7172141/thumbnails
      15k    ./XML_PRINTABLE/7172141
      20k    ./XML_PRINTABLE/MC0012407
      12k    ./XML_PRINTABLE/MC0012408
    512B    ./XML_PRINTABLE/7172144/thumbnails
    6.5k    ./XML_PRINTABLE/7172144
    4.0k    ./XML_PRINTABLE/INK0000281/thumbnails
      17k    ./XML_PRINTABLE/INK0000281
    512B    ./XML_PRINTABLE/7172143/thumbnails
      74k    ./XML_PRINTABLE/7172143
      12k    ./XML_PRINTABLE/MC0012405
      13k    ./XML_PRINTABLE/MC0012406
    239k    ./XML_PRINTABLE
    512B    ./XML_CMD
    512B    ./XML_REPORTS
    512B    ./XML_ORDERS_TEST
    512B    ./XML_ORDERS/MC0012405
    512B    ./XML_ORDERS/MC0012408
    512B    ./XML_ORDERS/MC0012402
    512B    ./XML_ORDERS/MC0012406
    512B    ./XML_ORDERS/MC0012410
    512B    ./XML_ORDERS/MC0012403
    512B    ./XML_ORDERS/MC0012409
    512B    ./XML_ORDERS/MC0012404
    272k    ./XML_ORDERS/7172141
    512B    ./XML_ORDERS/MC0012407
    454k    ./XML_ORDERS/7172142
    134M    ./XML_ORDERS
    512B    ./XML_INCOMING
    512B    ./XML_PRINTABLE_TEST
    5.0k    ./XML_JOBS/7172142/Preview
    6.0k    ./XML_JOBS/7172142
      26k    ./XML_JOBS/INK0000281/Preview
      27k    ./XML_JOBS/INK0000281
      40k    ./XML_JOBS/MC0012410/Preview
      41k    ./XML_JOBS/MC0012410
      39k    ./XML_JOBS/MC0012409/Preview
      40k    ./XML_JOBS/MC0012409
    116k    ./XML_JOBS
    135M    .

# zfs get compressratio data/XML_WORKFLOW
NAME               PROPERTY       VALUE  SOURCE
data/XML_WORKFLOW  compressratio  1.04x  -

If I didn't know better, and had not already tried to unmount/mount the 
zvol in question, I would swear this looked liked something mounting 
over the missing directories, similar to what can happen with a nfs 
mount that "disappears" on a client when there is a local directory of 
the same name.