# configuration file for dm-cache
#
# SPDX-License-Identifier: GPL-3.0-or-later
# Copyright 2023 Forza <forza@tnonline.net>
#
# Linux Cache admin documentation:
# https://www.kernel.org/doc/html/latest/admin-guide/device-mapper/cache.html
#

# Mandatory options are:
# dmname, cachedev, metadev, origindev

# The assembled dm-cache device name
# This will be available in /dev/mapper/<dmname>
dmname="dmcache1"

# The device to use as cache. Usually a fast
# SSad or NVME device
cachedev="/dev/disk/by-partlabel/cache"

# A small device used to store dm-cache metadata
metadev="/dev/disk/by-partlabel/meta"

# The origin block device. This is the slow device
# that should be accelerated with dm-cache.
# DO NOT use a filesystem uuid here, but a device ID.
# example:
# origindev="/dev/disk/by-partuuid/ac0ae9b1-8e32-4e33-b641-998bc0298d14"
# origindev="/dev/disk/by-id/ata-WDC_WD10JFCX-68N6GN0_WD-WX52A60PS33D-part1"
origindev="/dev/disk/by-partlabel/data"

# The following section has optional settings to tune the
# device-mapper options for assembling the cache. 
# These are advanced options. Make sure to read the Linux Cache 
# documentation before changing these.

# dm-cache requires the origindev size in 512 byte sectors.
originsize="$(/sbin/blockdev --getsz ${origindev})"

# Set read-ahead sectors for the mapped device.
# This does not change the read-ahead for the underlying
# devices.
#readahead=256

# Cache block size in 512 byte sectors.
# 256 sectors = 128KiB size cache blocks
#cacheblock=256

# Write cache mode: writeback, writethrough or passthrough.
#cachemode="1 writethrough"

# Migration policy decides when to migrate data to/from cache
# and origin device.
#cachepolicy="default"

# Additional policy arguments.
#cachepolicyargs="0"


# 'writethrough' cache (default):
#  Write through caching prohibits cachedev content from being
#  different from origindev content. This mode only accelerates
#  reads, but should allow the origin device to be used without the
#  cache dev after a crash. 
#
#  'writeback' cache:
#  When write back cache is used. Writes are written to the
#  cachedev first, before being synced in the background to the
#  origindev.
#  If the system crashes, the dm-cache must be assembled again
#  before use to avoid serious filesystem damage.
#  If the cachedev fails, the filesystem can be irrevokably damaged!