Why does dstat show zeroes for disk activity on my virtual private server running Ubuntu?

Question

I'm trying to monitor the number of disk reads and writes on my VPS (Rackspace in this case) running Ubuntu 9.04. I realize there are many tools to do this, but when using dstat 0.7 I tried the following command:

dstat -d

The output is just two columns of zeroes even when I upload a large file via scp that should be causing a large number of disk writes. Why is this, and how do I get dstat to correctly display the number of disk reads and writes?

Answer 1

dstat don't work in OpenVZ container. If you have access to host node, run:

# cat /proc/bc/556/ioacct 
read                           95322968064
write                        5023383080960
dirty                        5023383703552
cancel                       4862043058176
missed                                   0
syncs_total                             20
fsyncs_total                       1145489
fdatasyncs_total                   5842564
range_syncs_total                        0
syncs_active                             0
fsyncs_active                            0
fdatasyncs_active                        0
range_syncs_active                       0
vfs_reads                       7187138835
vfs_read_chars              56901570399853
vfs_writes                       777479552
vfs_write_chars              5636033128166
io_pbs                                 152