mariadb/plugin/information_schema_disks/README.txt
Alexey Botchkov 9652038453 MDEV-14533 Provide information_schema tables using which hardware
information can be obtained.

        DISKS plugin implementation added to the tree.
2018-03-21 12:33:38 +04:00

101 lines
4.1 KiB
Text

Information Schema Disks
------------------------
This is a proof-of-concept information schema plugin that allows the
disk space situation to be monitored. When installed, it can be used
as follows:
> select * from information_schema.disks;
+-----------+-----------------------+-----------+----------+-----------+
| Disk | Path | Total | Used | Available |
+-----------+-----------------------+-----------+----------+-----------+
| /dev/sda3 | / | 47929956 | 30666304 | 14805864 |
| /dev/sda1 | /boot/efi | 191551 | 3461 | 188090 |
| /dev/sda4 | /home | 174679768 | 80335392 | 85448120 |
| /dev/sdb1 | /mnt/hdd | 961301832 | 83764 | 912363644 |
| /dev/sdb1 | /home/wikman/Music | 961301832 | 83764 | 912363644 |
| /dev/sdb1 | /home/wikman/Videos | 961301832 | 83764 | 912363644 |
| /dev/sdb1 | /home/wikman/hdd | 961301832 | 83764 | 912363644 |
| /dev/sdb1 | /home/wikman/Pictures | 961301832 | 83764 | 912363644 |
| /dev/sda3 | /var/lib/docker/aufs | 47929956 | 30666304 | 14805864 |
+-----------+-----------------------+-----------+----------+-----------+
9 rows in set (0.00 sec)
- 'Disk' is the name of the disk itself.
- 'Path' is the mount point of the disk.
- 'Total' is the total space in KiB.
- 'Used' is the used amount of space in KiB, and
- 'Available' is the amount of space in KiB available to non-root users.
Note that as the amount of space available to root may be more that what
is available to non-root users, 'available' + 'used' may be less than 'total'.
All paths to which a particular disk has been mounted are reported. The
rationale is that someone might want to take different action e.g. depending
on which disk is relevant for a particular path. This leads to the same disk
being reported multiple times. An alternative to this would be to have two
tables; disks and mounts.
> select * from information_schema.disks;
+-----------+-----------+----------+-----------+
| Disk | Total | Used | Available |
+-----------+-----------+----------+-----------+
| /dev/sda3 | 47929956 | 30666304 | 14805864 |
| /dev/sda1 | 191551 | 3461 | 188090 |
| /dev/sda4 | 174679768 | 80335392 | 85448120 |
| /dev/sdb1 | 961301832 | 83764 | 912363644 |
+-----------+-----------+----------+-----------+
> select * from information_schema.mounts;
+-----------------------+-----------+
| Path | Disk |
+-----------------------+-----------+
| / | /dev/sda3 |
| /boot/efi | /dev/sda1 |
| /home | /dev/sda4 |
| /mnt/hdd | /dev/sdb1 |
| /home/wikman/Music | /dev/sdb1 |
...
Building
--------
- Ensure that the directory information_schema_disks is in the top-level
directory of the server.
- Add
ADD_SUBDIRECTORY(information_schema_disks)
to the top-level CMakeLists.txt
> Invoke make
$ make
Installation
------------
- Copy information_schema_disks/libinformation_schema_disks.so to the plugin
directory of the server:
$ cd information_schema_disks
$ sudo cp libinformation_schema_disks.so plugin-directory-of-server
- Using mysql, install the plugin:
MariaDB [(none)]> install plugin disks soname 'libinformation_schema_disks.so';
Usage
-----
The plugin appears as the table 'disks' in 'information_schema'.
MariaDB [(none)]> select * from information_schema.disks;
+-----------+-----------------------+-----------+----------+-----------+
| Disk | Path | Total | Used | Available |
+-----------+-----------------------+-----------+----------+-----------+
| /dev/sda3 | / | 47929956 | 30666308 | 14805860 |
| /dev/sda1 | /boot/efi | 191551 | 3461 | 188090 |
| /dev/sda4 | /home | 174679768 | 80348148 | 85435364 |
| /dev/sdb1 | /mnt/hdd | 961301832 | 83764 | 912363644 |
| /dev/sdb1 | /home/wikman/Music | 961301832 | 83764 | 912363644 |
| /dev/sdb1 | /home/wikman/Videos | 961301832 | 83764 | 912363644 |
...