This makes ioztat output more closely resemble zpool iostat:

                              operations      bandwidth         opsize
dataset                       read   write    read   write    read   write
--------------------------  ------  ------  ------  ------  ------  ------
rpool
   ROOT
      default                   23       0   62.6K       0    2.7K     759
   cvs                           0       0    1.6K     892   24.2K  108.4K
   home                          0       0       0       0       0       0
      freaky                     3       2   29.7K    8.3K   10.2K    3.9K

This also adds -e for exact values (-p in zpool iostat, which we're currently using elsewhere) and -H for scripted mode that drops the header and separates fields by tabs.

The intent is for this to eventually fix #23, probably by adjusting the space for dataset.

Should bandwidth be changed to throughput? This is more correct, but deviates from zpool-iostat(8).

Should we default to binary mode, since that's all zpool-iostat(8) supports?

Should we default to a single iteration? This is what iostat(1) and zpool-iostat(8) both do. They also accept interval and count as positional arguments.

Is + as an ellipsis for truncated dataset names reasonable, or should it be ... despite the additional space it uses?

I thought that this script put a little too much into the terminal. This PR makes it so that only the most recent report is visible, which can be disabled with the new -n argument.

ioztat -Hey as suggested by the man page doesn't return anything.

ioztat -SIn rpool, also suggested by the man page, gives "dataset not found: 'rpool'" (rpool of course exists).

Is there a way to further debug this? Am I missing a dependency?

Matching ZFS number formatting behaviour, use between 0 and 2 decimal places according to available space, and further reduce the column size to again match zpool-iostat and make more room for dataset names.

This includes the careful rounding behaviour of the previous implementation, which I believe ZFS lacks.

Fix an error when args.count is None. While I'm here also fix a count of zero that was ignored due to zero being falsey.

Simplify the logic slightly by changing skipsummary from a bool to a generic skip count.

The current output width is 106 columns, which by happy coincidence is precisely the width of my usual terminals.

This coincidence seems unlikely to be universal, and some sensitivity to this would seem to be in order.

This fixes overwrite mode by replacing the line counting and iterated cursor repositioning with a clear screen and placing the cursor at 1,1 - exactly what GNU watch does.

I've also done some tidying, hoisting some iteration and filtering logic into dedicated generator functions which helps to further simplify the main loop.

@Freaky, I discovered after merging your patches today that ioztat does not work on the Python2.7 that my Ubuntu workstation at the home office provides with "env python". I had to update the shebang to "env python3" to get it to work again.

This should be fine for Ubuntu, but does it work in FreeBSD-land as well? I don't know if there's a python3 executable in your environment, or whether there is only python and you get what you get.

Fixes #5

This replaces the "just-the-rightmost-dataset-name-component" logic by "components-of-the-name-unique-after-the-previous-one". Output with default options looks like

dataset                                         w/s      wMB/s        r/s      rMB/s   wareq-sz   rareq-sz
zroot                                          0.00       0.00       0.00       0.00       0.00       0.00
   ROOT/default                                0.00       0.00       3.88       0.00       0.00       0.16
   tmp                                         0.00       0.00       0.00       0.00       0.00       0.00

(e.g. here instead of default being indented two, and ROOT being invisible, we get the dataset-name-components that distinguish it from zroot, the previously-printed name)

Stats for unmounted datasets aren't exported, so you can end up with incomplete hierarchies in ioztat output. For example here rpool and rpool/ROOT aren't mounted, leaving rpool/ROOT/default without the path leading up to it:

dataset                                         w/s      wMB/s        r/s      rMB/s   wareq-sz   rareq-sz
      default                                  0.00       0.00       0.97       0.00       0.00       0.05

Similarly, rpool/usr/local/poudriere/ports/default misses the mountpoint-less poudriere/ports segments:

   usr                                         0.00       0.00       0.97       0.00       0.00       0.01
      local                                    0.00       0.00       0.00       0.00       0.00       0.00
               default                         0.00       0.00       0.00       0.00       0.00       0.00

Hi,

I started of my own version of this, but found yours basically the last moment … My name of choice was objset, but the poll is finished I guess.

I used dataclasses - ported here. And updated the fields to match current OpenZFS git.

is it expected that ioztat does not seem to report activity for zfs replication ?

if this is not a bug but by design, maybe it's worth mentioning in the

Produce .deb/.rpm/etc packages. sanoid is already doing this. I'm currently using sanoid package in latest ubuntu release.

Getting these included will take some time but is worthwhile I think.