MDEV-14533 Provide information_schema tables using which hardware information can be obtained.

update README, use maria_declare_plugin(), specify the author.

1 files changed, 86 insertions, 0 deletions

diff --git a/plugin/disks/README.txt b/plugin/disks/README.txt
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+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 |
+  ...
+
+
+Installation
+------------
+
+- Use "install plugin" or "install soname" command:
+
+  MariaDB [(none)]> install plugin disks soname 'disks.so';
+
+  or
+
+  MariaDB [(none)]> install soname '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 |
+  ...
+