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The cockroach debug ballast
command creates a large, unused file that you can place in a node's storage directory. In the case that a node runs out of disk space and shuts down, you can delete the ballast file to free up enough space to be able to restart the node.
- Do not run
cockroach debug ballast
with a unixroot
user. Doing so brings the risk of mistakenly affecting system directories or files. - Do not name the target file similar to a block device in
/dev
. Doing so brings the risk of mistyping a/dev
prefix into the command and thereby corrupting a filesystem. - In addition to placing a ballast file in each node's storage directory, it is important to actively monitor remaining disk space.
- Ballast files may be created in many ways, including the standard
dd
command.cockroach debug ballast
uses thefallocate
system call when available, so it will be faster thandd
.
Subcommands
While the cockroach debug
command has a few subcommands, users are expected to use only the zip
, encryption-active-key
, merge-logs
, and ballast
subcommands.
The other debug
subcommands are useful only to CockroachDB's developers and contributors.
Synopsis
Create a ballast file:
$ cockroach debug ballast [path to ballast file] [flags]
View help:
$ cockroach debug ballast --help
Flags
Flag | Description |
---|---|
--size -z |
The amount of space to fill, or to leave available, in a node's storage directory via a ballast file. Positive values equal the size of the ballast file. Negative values equal the amount of space to leave after creating the ballast file. This can be a percentage (notated as a decimal or with %) or any bytes-based unit, for example:--size=1000000000 ----> 1000000000 bytes --size=1GiB ----> 1073741824 bytes --size=5% ----> 5% of available space --size=0.05 ----> 5% of available space --size=.05 ----> 5% of available space |
Example
$ cockroach debug ballast cockroach-data/ballast.txt --size=1GiB