ioztat
ioztat is a storage load analysis tool for OpenZFS. It provides iostat-like statistics at an individual dataset/zvol level.
The statistics offered are read and write operations per second, read and write throughput per second, and the average size of read and write operations issued in the current reporting interval. Viewing these statistics at the individual dataset level allows system administrators to identify storage "hot spots" in larger multi-tenant systems--particularly those with many VMs or containers operating essentially independent workloads.
This sample output shows activity which has taken place in the most recent second, on a the ssd zpool of a ZFS virtualization host:
root@redacted-prod0:~# ioztat -y ssd
operations throughput opsize
dataset read write read write read write
---------------- ----- ----- ----- ----- ----- -----
ssd 0 0 0 0 0 0
images 0 0 0 0 0 0
DC1 4 18 49.0K 98.0K 12.5K 5.56K
DC2 0 22 0 137K 0 6.36K
QB 0 2 0 9.80K 0 5.00K
SAP-TC 0 3 0 19.6K 0 6.67K
SAP4-WIN2019 0 3 0 49.0K 0 16.7K
nagios 0 0 0 0 0 0
qemu 0 0 0 0 0 0
autostart 0 0 0 0 0 0
iso 0 0 0 0 0 0
unsnapped 0 0 0 0 0 0
rp9 0 0 0 0 0 0
---------------- ----- ----- ----- ----- ----- -----
For the most part, ioztat behaves the same way that the system standard iostat tool does, with similar arguments.
usage: ioztat [-c COUNT] [-D] [-e] [-H] [-h] [-I] [-i INTERVAL] [-N] [-n] [-o] [-P | -p] [-S]
[-s {name,operations,reads,writes,throughput,nread,nwritten}] [-T {u,d}] [-V] [-y] [-z]
[dataset [dataset ...]] [interval [count]]
iostat for ZFS datasets
positional arguments:
dataset ZFS dataset
interval [count] seconds between reports and number of reports
optional arguments:
-c COUNT number of reports generated
-D display bytes in decimal powers of 1000 instead of 1024
-e display exact values without truncation or scaling
-H scripted mode, omit headers and tab-separate fields
-h, --help display this help message and exit
-I display totals since the last update rather than averaged per-second
-i INTERVAL interval between reports (in seconds)
-N display headers at most once
-n omit child datasets when filtering
-o overwrite old reports in terminal
-P display dataset names on a single line
-p display dataset names as an abbreviated tree
-S include statistics for child datasets in parents
-s {name,operations,reads,writes,throughput,nread,nwritten}
sort by the specified field
-T {u,d} prefix each report with a Unix timestamp or formatted date
-V, --version display version number and exit
-y omit the initial "summary" report
-z omit datasets with zero activity
Without arguments, ioztat prints a summary of activity for each mounted dataset since the most recent system boot and exits.
With an optional interval, ioztat will repeat reports on that schedule until interrupted, or up to a specified count. If only a count is specified, the interval defaults to one second. Interval and count can be specified with -i and -c or as positional arguments at the very end of the argument list.
The -o flag will overwrite prior output and limit the display to the terminal height. This can be combined with an interval and sorting options for an iotop-like experience.