salt.modules.bcache module

Module for managing BCache sets

BCache is a block-level caching mechanism similar to ZFS L2ARC/ZIL, dm-cache and fscache. It works by formatting one block device as a cache set, then adding backend devices (which need to be formatted as such) to the set and activating them.

It's available in Linux mainline kernel since 3.10

https://www.kernel.org/doc/Documentation/bcache.txt

This module needs the bcache userspace tools to function.

salt.modules.bcache.attach(dev=None)

Attach a backing devices to a cache set If no dev is given, all backing devices will be attached.

CLI example:

salt '*' bcache.attach sdc
salt '*' bcache.attach /dev/bcache1
Returns:bool or None if nuttin' happened
salt.modules.bcache.back_make(dev, cache_mode=u'writeback', force=False, attach=True, bucket_size=None)

Create a backing device for attachment to a set. Because the block size must be the same, a cache set already needs to exist.

CLI example:

salt '*' bcache.back_make sdc cache_mode=writeback attach=True
Parameters:
  • cache_mode -- writethrough, writeback, writearound or none.
  • force -- Overwrite existing bcaches
  • attach -- Immediately attach the backing device to the set
  • bucket_size -- Size of a bucket (see kernel doc)
salt.modules.bcache.cache_make(dev, reserved=None, force=False, block_size=None, bucket_size=None, attach=True)

Create BCache cache on a block device. If blkdiscard is available the entire device will be properly cleared in advance.

CLI example:

salt '*' bcache.cache_make sdb reserved=10% block_size=4096
Parameters:
  • reserved --

    if dev is a full device, create a partition table with this size empty.

    Note

    this increases the amount of reserved space available to SSD garbage collectors, potentially (vastly) increasing performance

  • block_size -- Block size of the cache; defaults to devices' logical block size
  • force -- Overwrite existing BCache sets
  • attach -- Attach all existing backend devices immediately
salt.modules.bcache.config(dev=None, **kwargs)

Show or update config of a bcache device.

If no device is given, operate on the cache set itself.

CLI example:

salt '*' bcache.config
salt '*' bcache.config bcache1
salt '*' bcache.config errors=panic journal_delay_ms=150
salt '*' bcache.config bcache1 cache_mode=writeback writeback_percent=15
Returns:config or True/False
salt.modules.bcache.detach(dev=None)

Detach a backing device(s) from a cache set If no dev is given, all backing devices will be attached.

Detaching a backing device will flush it's write cache. This should leave the underlying device in a consistent state, but might take a while.

CLI example:

salt '*' bcache.detach sdc
salt '*' bcache.detach bcache1
salt.modules.bcache.device(dev, stats=False, config=False, internals=False, superblock=False)

Check the state of a single bcache device

CLI example:

salt '*' bcache.device bcache0
salt '*' bcache.device /dev/sdc stats=True
Parameters:
  • stats -- include statistics
  • settings -- include all settings
  • internals -- include all internals
  • superblock -- include superblock info
salt.modules.bcache.start()

Trigger a start of the full bcache system through udev.

CLI example:

salt '*' bcache.start
salt.modules.bcache.status(stats=False, config=False, internals=False, superblock=False, alldevs=False)

Show the full status of the BCache system and optionally all it's involved devices

CLI example:

salt '*' bcache.status
salt '*' bcache.status stats=True
salt '*' bcache.status internals=True alldevs=True
Parameters:
  • stats -- include statistics
  • config -- include settings
  • internals -- include internals
  • superblock -- include superblock
salt.modules.bcache.stop(dev=None)

Stop a bcache device If no device is given, all backing devices will be detached from the cache, which will subsequently be stopped.

Warning

'Stop' on an individual backing device means hard-stop; no attempt at flushing will be done and the bcache device will seemingly 'disappear' from the device lists

CLI example:

salt '*' bcache.stop
salt.modules.bcache.super(dev)

Read out BCache SuperBlock

CLI example:

salt '*' bcache.device bcache0
salt '*' bcache.device /dev/sdc
salt.modules.bcache.uuid(dev=None)

Return the bcache UUID of a block device. If no device is given, the Cache UUID is returned.

CLI example:

salt '*' bcache.uuid
salt '*' bcache.uuid /dev/sda
salt '*' bcache.uuid bcache0