very diferent results from df after few seconds
- by tatus2
When the backup moves the files from one to the other server the results from df changing every some seconds in impossible manner. On source host is running rsync. On destination host I'm running every few seconds following command:
echo `date` `df|grep md0`
Results are below:
Sat Jun 29 23:57:12 CEST 2013 /dev/md0 4326425568 579316100 3527339636 15% /MD0
Sat Jun 29 23:57:14 CEST 2013 /dev/md0 4326425568 852513700 3254142036 21% /MD0
Sat Jun 29 23:57:15 CEST 2013 /dev/md0 4326425568 969970340 3136685396 24% /MD0
Sat Jun 29 23:57:17 CEST 2013 /dev/md0 4326425568 1255222180 2851433556 31% /MD0
Sat Jun 29 23:57:20 CEST 2013 /dev/md0 4326425568 1276006720 2830649016 32% /MD0
Sat Jun 29 23:57:24 CEST 2013 /dev/md0 4326425568 1355440016 2751215720 34% /MD0
Sat Jun 29 23:57:26 CEST 2013 /dev/md0 4326425568 1425090960 2681564776 35% /MD0
Sat Jun 29 23:57:27 CEST 2013 /dev/md0 4326425568 1474601872 2632053864 36% /MD0
Sat Jun 29 23:57:28 CEST 2013 /dev/md0 4326425568 1493627384 2613028352 37% /MD0
Sat Jun 29 23:57:32 CEST 2013 /dev/md0 4326425568 615934400 3490721336 15% /MD0
Sat Jun 29 23:57:33 CEST 2013 /dev/md0 4326425568 636071360 3470584376 16% /MD0
as you can see I start from USE of 15% and after 15 seconds I'm at 37% (I don't need to mention that the backup can not copy this huge amount of data in so short time). After ~20 sec the cycle closes. I'm again roughly by the same usage as earlier. The value is reasonable ca. 35 Mb were copied.
Can somebody explain me what is going on? Does df only make an estimation of usage instead of used value?
