Hello list,
lscp's "-g, --show-increment" option seems to give misleading number
of appended blocks, significantly under-counting disk usage. i
expected the sum total of increments, plus the full size of the first
checkpoint, multiplied by block size (4096 in my case) to be equal to
total used disk space (or slightly below it, due to partly used
segments). and while the size of each checkpoint is indeed roughly
equal to disk use by that checkpoint, the sum of increments
significantly undercounts disk space usage.
am i using it wrong, or is it bugged?
using latest kernel and long-running filesystems
example from one of my computers: 170GB calculated vs 356GB actual use
Nr checkpoints: 49477
Oldest checkpoint used space [MB]: 141903
Computed sum increments used space [MB]: 28777
Computed sum total used space [MB]: 170680
Actual used space reported by df -m [MB]: 354072
example from another of my computers: 34GB calculated vs 119GB actual use
Nr checkpoints: 2368
Oldest checkpoint used space [MB]: 27520
Computed sum increments used space [MB]: 6813
Computed sum total used space [MB]: 34334
Actual used space reported by df -m [MB]: 119040
repro script:
#!/bin/sh
fs=`df . | awk 'NR==2 {print $1}'`
lscp $fs | awk 'END {print "Nr checkpoints: " NR-1}'
lscp --all $fs | awk 'NR==2 {print $6}' | awk '{printf("Oldest
checkpoint used space [MB]: %15d\n", ($1*4096)/1024/1024)}'
lscp --all --show-increment $fs | head -n-1 | awk 'NR>2 {sum=sum+$6}
END {print sum}' | awk '{printf("Computed sum increments used space
[MB]: %9d\n", ($1*4096)/1024/1024)}'
{
lscp --all $fs | awk 'NR==2 {print $6}'
lscp --all --show-increment $fs | head -n-1 | awk 'NR>2 {print $6}'
} | awk '{sum=sum+$1} END { printf("Computed sum total used space
[MB]: %14d\n", (sum*4096)/1024/1024)}'
df -m $fs | awk 'NR==2 {printf("Actual used space reported by df -m
[MB]: %8d\n", $3)}'
cheers,
--
dexen
