Configuration Tool Details

The Open CAS Linux product includes a user-level configuration tool that provides complete control of the caching software. The commands and parameters available with this tool are detailed in this chapter.

To access help from the CLI, type the -H or --help parameter for details. You can also view the man page for this product by entering the following command:

# man casadm

-S | --start-cache

Usage: casadm --start-cache --cache-device <DEVICE> [option…]

Example:

# casadm --start-cache --cache-device /dev/disk/by-id/nvme-SSD

# casadm -S -d /dev/disk/by-id/nvme-SSD

Description: Prepares a block device to be used as device for caching other block devices. Typically the cache devices are SSDs or other NVM block devices or RAM disks. The process starts a framework for device mappings pertaining to a specific cache ID. The cache can be loaded with an old state when using the -l or --load parameter (previous cache metadata will not be marked as invalid) or with a new state as the default (previous cache metadata will be marked as invalid).

Required Parameters:

[-d, --cache-device <DEVICE>] : Caching device to be used. This is an SSD or any NVM block device or RAM disk shown in the /dev/disk/by-id directory. <device> needs to be the complete path describing the caching device to be used, for example /dev/disk/by-id/nvme-SSD.

Optional Parameters:

[-i, --cache-id <ID>]: Cache ID to create; <1 to 16384>. The ID may be specified or by default the command will use the lowest available number first.

[-l, --load]: Load existing cache metadata from caching device. If the cache device has been used previously and then disabled (like in a reboot) and it is determined that the data in the core device has not changed since the cache device was used, this option will allow continuing the use of the data in the cache device without the need to re-warm the cache with data.

Caution: You must ensure that the last shutdown followed the instructions in section Stopping Cache Instances. If there was any change in the core data prior to enabling the cache, data would be not synced correctly and will be corrupted.

[-f, --force]: Forces creation of a cache even if a file system exists on the cache device. This is typically used for devices that have been previously utilized as a cache device.

Caution: This will delete the file system and any existing data on the cache device.

[-c, --cache-mode <NAME>]: Sets the cache mode for a cache instance the first time it is started or created. The mode can be one of the following:

wt: (default mode) Turns write-through mode on. When using this parameter, the write-through feature is enabled which allows the acceleration of only read intensive operations.

wb: Turns write-back mode on. When using this parameter, the write-back feature is enabled which allows the acceleration of both read and write intensive operations.

Caution: A failure of the cache device may lead to the loss of data that has not yet been flushed to the core device.

wa: Turns write-around mode on. When using this parameter, the write-around feature is enabled which allows the acceleration of reads only. All write locations that do not already exist in the cache (i.e. the locations have not be read yet or have been evicted), are written directly to the core drive bypassing the cache. If the location being written already exists in cache, then both the cache and the core drive will be updated.

pt: Starts cache in pass-through mode. Caching is effectively disabled in this mode. This allows the user to associate all their desired core devices to be cached prior to actually enabling caching. Once the core devices are associated, the user would dynamically switch to their desired caching mode (see ‘-Q | --set-cache-mode’ for details).

wo: Turns write-only mode on. When using this parameter, the write-only feature is enabled which allows the acceleration of write intensive operations primarily.

Caution: A failure of the cache device may lead to the loss of data that has not yet been flushed to the core device.

[-x, --cache-line-size <SIZE>]: Set cache line size {4 (default), 8, 16, 32, 64}. The cache line size can only be set when starting the cache and cannot be changed after cache is started.

-T | --stop-cache

Usage: casadm --stop-cache --cache-id <ID> [option…]

Example:

# casadm --stop-cache --cache-id 1

# casadm -T -i 1

Description: Stops all cache-core pairs associated with the cache device.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional parameters:

[-n, --no-data-flush]: Do not flush dirty data on exit (UNSAFE). This parameter will not allow the flushing of dirty data from the cache device to the core device upon the stopping of the cache. This will significantly reduce the time needed to stop the cache to allow for activities such as a fast reboot. The core device should not be used until the cache is started again with the --load parameter. Then the Open CAS Linux device can be used as normal.

Caution: Data on the core device will not be complete or in sync with the cache device upon stopping the device. If the core device is used without starting Open CAS Linux cache it will lead to data corruption or data loss.
The user may interrupt the blocking --stop-cache operation by pressing CTRL-C. When dirty data exists, interrupting the operation prior to the cache being fully stopped will result in the cache continuing to run. If the desire is to stop the cache without flushing the dirty data, use the --no-data-flush command.

-Q | --set-cache-mode

Usage: casadm --set-cache-mode --cache-mode <NAME> --cache-id <ID> --flush-cache <yes/no>

Example:

# casadm --set-cache-mode --cache-mode wb --cache-id 1 --flush-cache yes

# casadm -Q -c wb -i 1 -f yes

Description: Allows users to dynamically change cache modes while the cache is running.

Required Parameters:

[-c, --cache-mode <NAME>]:

wt - switch from the current cache mode to write-through mode.
wb - switch from the current cache mode to write-back mode.
wo - switch from the current cache mode to write-only mode.
wa - switch from the current cache mode to write-around mode
pt - switch from the current cache mode to pass-through mode.
- Dynamically switching to pass-through mode is useful in preventing cache pollution when the system is undergoing maintenance operations, for example.

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>

[-f, --flush-cache]: (required only when switching from write-back mode)

Caution: You should carefully consider the following choices.

yes - Flush cache contents immediately to core drive before switching to new cache mode.
- When choosing yes to flush the cache immediately, the operation may take a long time to complete depending on number of dirty blocks. IO to the device will continue at reduced performance until flush completes.
no - Begin transition to new cache mode immediately, but flush cache contents opportunistically.
- When choosing no, IO to the device will continue at normal performance, but you must be aware that the cache will be in a transition state, and not yet in the newly chosen state until the cache is fully flushed. The transition to the new state will take longer than choosing the yes option. Current cache state and flush % can be checked using the casadm -L command.

-A | --add-core

Usage: casadm --add-core --cache-id <ID> --core-device <DEVICE> [option…]

Example:

# casadm --add-core --cache-id 1 --core-device /dev/disk/by-id/wwn-0x50014ee004276c68

# casadm -A -i 1 -d /dev/disk/by-id/wwn-0x50014ee004276c68

Description: Adds/maps a core device (either the full device or a partition) to the framework associated with a specified cache ID. This command can be repeated using the same cache-id number to map multiple cores to the same cache device.

Required Parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

[-d, --core-device <DEVICE>]: Location of the HDD storage/core device.
You must use the complete device path in the /dev/disk/by-id directory, for example /dev/disk/by-id/wwn-0x50014ee004276c68.

Optional Parameters:

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>.

-R | --remove-core

Usage: casadm --remove-core --cache-id <ID> --core-id <ID> [option…]

Example:

# casadm --remove-core --cache-id 1 --core-id 1

# casadm -R -i 1 -j 1

Description: Deletes the cache/core device mapping, which is one way to disable caching of a device.

Required Parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>.
You can identify the assigned value for a particular core device using the casadm -L command.

Caution: Before using casadm -R, stop all IO to the mapped core device, ensure it is not in use, and unmount it.
You can interrupt the blocking --remove-core operation by pressing CTRL-C. When dirty data exists, interrupting the operation prior to the core being fully removed will result in the core continuing to be cached.
Although legal core ID range starts with 0, Open CAS Linux engine would resort to assigning core ID value
of 0 only if all other core IDs within cache instance are used. In other words the order of core assignment is as follows: 1, 2, 3, …, 4094, 4095, 0.

Optional parameters:

[-f, --force]: Do not flush dirty data while removing the core device.

--remove-detached

Usage: casadm --remove-detached --device <DEV_NAME>

Example:

# casadm --remove-detached --device /dev/disk/by-id/wwn-0x50014ee0042769ef

# casadm --remove-detached -d /dev/disk/by-id/wwn-0x50014ee0042769ef

Description: Removes a device from the core pool. A device is in the core pool when it’s listed in opencas.conf as a core in a configured cache instance, and this cache instance is not yet started (for example, missing the NVMe drive). This command does not currently have a short form.

Required Parameters:

-d | --device <DEV_NAME>

Where DEV_NAME is a device name from the core pool

--remove-inactive

Usage: casadm --remove-inactive --device <DEV_NAME>

Example:

# casadm --remove-detached --cache-id 1 --core-id 1

# casadm --remove-detached -i 1 -j 1

Description: Deletes the cache/inactive core device mapping, which is one way to disable caching of an inactive device.

Required Parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>.
You can identify the assigned value for a particular core device using the casadm -L command.

Caution: Before using casadm --remove-inactive, stop all IO to the mapped core device, ensure it is not in use, and unmount it.
Although legal core ID range starts with 0, Open CAS Linux engine would resort to assigning core ID value of 0 only if all other core IDs within cache instance are used. In other words the order of core assignment is as follows: 1, 2, 3, …, 4094, 4095, 0.

-L | --list-caches

Usage: casadm --list-caches

Example:

# casadm --list-caches

# casadm -L

Description: Displays each cache instance with the following details:

Flash/SSD cache ID used in the instance
Storage device used in the instance
Status of the instance
Write Policy of the instance (write-through by default)

Also displays the associated core devices with the following details:

Core Pool label
Numeric ID and disk name
Status
Open CAS Linux exported device ID
Placement within the core pool

Example output:

type id disk status write policy device

cache 1 /dev/nvme0n1p1 Incomplete wt -

+core 1 /dev/disk/by-id/wwn-0x500….-part1 Inactive - /dev/cas1-1

+core 2 /dev/sdc1 Active - /dev/cas1-2

-P | --stats

Usage: casadm --stats --cache-id <ID> [option…]

Example:

# casadm --stats --cache-id 1

# casadm -P -i 1

Description: Prints performance and status counters for a specific cache instance. The section Viewing Cache Statistics shows the detailed output.

Required Parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters:

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>. Display statistics for a specific core device.

[-d, --io-class-id <ID>]: Unique identifier for io class <0 to 23>. Display statistics for a specific IO class.

<ID> is optional. When the --io-class-id parameter is specified without specifying an <ID>, statistics will be displayed for each individual IO class.

[-f, --filter <filter-spec>]: Comma separated list of filters (e.g., --filter conf, req). Filter statistics output to only the requested statistics.

all: (default mode) Displays all available cache statistics.
conf: Displays cache and core configuration information and dirty timestamp.
usage: Displays statistics on occupancy, free, clean, and dirty.
req: Displays IO request level statistics.
blk: Displays block level statistics.
err: Displays IO error statistics.

[-o, --output-format <format>]: Sets desired output format for statistics.

table: (default mode) Displays a table of the statistics information.
csv: Outputs a comma separated list of statistics information. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

Example output:

# casadm -P -i 1

Cache Id                  1
Cache Size                43708 [4KiB Blocks] / 0.17 [GiB]
Cache Device              /dev/nvme0n1p1
Core Devices              2
Inactive Core Devices     1
Write Policy              wt
Eviction Policy           lru
Cleaning Policy           alru
Cache line size           4 [KiB]
Metadata Memory Footprint 19.6 [MiB]
Dirty for                 0 [s] / Cache clean
Metadata Mode             normal
Status                    Incomplete
+==================+=======+=======+=============+
| Usage statistics | Count |   %   |   Units     |
+==================+=======+=======+=============+
| Occupancy        |   164 |   0.4 | 4KiB blocks |
| Free             | 43544 |  99.6 | 4KiB blocks |
| Clean            |   164 | 100.0 | 4KiB blocks |
| Dirty            |     0 |   0.0 | 4KiB blocks |
+==================+=======+=======+=============+
+===========================+=======+======+=============+
| Inactive usage statistics | Count |  %   |   Units     |
+===========================+=======+======+=============+
| Inactive Occupancy        |    82 |  0.2 | 4KiB blocks |
| Inactive Clean            |    82 | 50.0 | 4KiB blocks |
| Inactive Dirty            |     0 |  0.0 | 4KiB blocks |
+===========================+=======+======+=============+
+======================+=======+=======+==========+
| Request statistics   | Count |   %   | Units    |
+======================+=======+=======+==========+
| Read hits            |   328 |  99.7 | Requests |
| Read partial misses  |     0 |   0.0 | Requests |
| Read full misses     |     0 |   0.0 | Requests |
| Read total           |   328 |  99.7 | Requests |
+----------------------+-------+-------+----------+
| Write hits           |     0 |   0.0 | Requests |
| Write partial misses |     0 |   0.0 | Requests |
| Write full misses    |     0 |   0.0 | Requests |
| Write total          |     0 |   0.0 | Requests |
+----------------------+-------+-------+----------+
| Pass-Through reads   |     1 |   0.3 | Requests |
| Pass-Through writes  |     0 |   0.0 | Requests |
| Serviced requests    |   328 |  99.7 | Requests |
+----------------------+-------+-------+----------+
| Total requests       |   329 | 100.0 | Requests |
+======================+=======+=======+==========+
+==================================+=======+=======+=============+
| Block statistics                 | Count |   %   |   Units     |
+==================================+=======+=======+=============+
| Reads from core(s)               |     1 | 100.0 | 4KiB blocks |
| Writes to core(s)                |     0 |   0.0 | 4KiB blocks |
| Total to/from core(s)            |     1 | 100.0 | 4KiB blocks |
+----------------------------------+-------+-------+-------------+
| Reads from cache                 |    82 | 100.0 | 4KiB blocks |
| Writes to cache                  |     0 |   0.0 | 4KiB blocks |
| Total to/from cache              |    82 | 100.0 | 4KiB blocks |
+----------------------------------+-------+-------+-------------+
| Reads from exported object(s)    |    83 | 100.0 | 4KiB blocks |
| Writes to exported object(s)     |     0 |   0.0 | 4KiB blocks |
| Total to/from exported object(s) |    83 | 100.0 | 4KiB blocks |
+==================================+=======+=======+=============+
+====================+=======+=====+==========+
| Error statistics   | Count |  %  | Units    |
+====================+=======+=====+==========+
| Cache read errors  |     0 | 0.0 | Requests |
| Cache write errors |     0 | 0.0 | Requests |
| Cache total errors |     0 | 0.0 | Requests |
+--------------------+-------+-----+----------+
| Core read errors   |     0 | 0.0 | Requests |
| Core write errors  |     0 | 0.0 | Requests |
| Core total errors  |     0 | 0.0 | Requests |
+--------------------+-------+-----+----------+
| Total errors       |     0 | 0.0 | Requests |
+====================+=======+=====+==========+

-Z | --reset-counters

Usage: casadm --reset-counters --cache-id <CACHE_ID> [--core-id <CORE_ID>]

Example:

# casadm --reset-counters --cache-id 1

# casadm -Z -i 1

Description: Resets performance and status counters for specific cache/core pairs.

Required Parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters:

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>. If a core(s) is not specified, statistic counters are reset for all cores in a specified cache instance.

-F | --flush-cache

Usage: casadm --flush-cache --cache-id <CACHE_ID> [--core-id <CORE_ID>]

Example:

# casadm --flush-cache --cache-id 1

# casadm -F -i 1

# casadm -F -i 1 -j 1

Description: Flushes all dirty data from the cache device to all the associated core devices.

Required Parameters:

[-i, --cache-id <CACHE_ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters

[-j, --core-id <CORE_ID>]: Unique identifier for core <0 to 4095>. If is provided, flushes all dirty data from specified cache device to the specified associated core device.

You can interrupt the blocking --flush-cache operation by pressing CTRL-C. When dirty data exists, interrupting the operation prior to the cache being fully flushed will result in some dirty data remaining in the cache. The dirty data will be flushed opportunistically as normal. IO to the device will continue with reduced performance during cache flushing.

--zero-metadata

Usage: casadm --zero-metadata --device <DEV_NAME> [option]

Example:

# casadm --zero-metadata --device /dev/disk/by-id/wwn-0x50014ee0042769ef

# casadm --zero-metadata -d /dev/disk/by-id/wwn-0x50014ee0042769ef

Description: Clears metadata from the caching device. This command does not currently have a short form.

Required Parameters:

-d | --device <DEV_NAME>

Where DEV_NAME is a device name from the core pool

Optional parameters:

[-f, --force]: Forces clearing metadata from a cache device even if a potential dirty data system exists on the cache device. This is typically used for devices that have been previously utilized as a cache device.

Caution: This will delete and any existing metadata on the cache device.

-H | --help

Usage: casadm --help or casadm --<command> --help

Examples:

# casadm --help

# casadm -H

# casadm --start-cache --help

# casadm -S -H

Description: Displays a list of casadm commands along with a brief description. Use this command to also get more information on specific commands.

-V | --version

Usage: casadm --version

Example:

# casadm --version

# casadm -V

Description: Reports the Open CAS Linux kernel module and command line utility version numbers.

Optional parameters:

[-o, --output-format <format>]: Sets desired output format of the IO class configuration.

table: (default mode) Displays a table of the IO class configuration.
csv: Outputs a comma separated list of the IO class configuration. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

-C | --io-class

-C | --load-config

Usage: casadm --io-class --load-config --cache-id <ID> --file <file_path>

Example:

# casadm --io-class --load-config --cache-id 1 --file ioclass-config.csv

# casadm -C -C -i 1 -f ioclass-config.csv

Description: Loads IOclass configuration settings for the selected cache.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

[-f,--file]: Specifies the IO class configuration csv file to load.

-L | --list

Usage: casadm --io-class --list --cache-id <ID> [option…]

Example:

# casadm --io-class --list --cache-id 1

# casadm -C -L -i 1

Description: Displays the current IO class configuration settings for the specified cache ID.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional parameters:

[-o, --output-format <format>]: Sets desired output format of the IO class configuration.

table: (default mode) Displays a table of the IO class configuration.
csv: Outputs a comma separated list of the IO class configuration. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

-X | --set-param

Description: Used in conjunction with caching parameters or namespaces to set cache policies. This command is targeted to add additional parameters in future releases. See applicable configuration details below.

seq-cutoff

Usage: casadm --set-param --name seq-cutoff --cache-id <CACHE_ID> [--core-id <CORE_ID>] [--policy <POLICY>] [--threshold <THRESHOLD>] [--promotion-count <NUMBER>]

Example:

# casadm --set-param --name seq-cutoff --cache-id 1 --core-id 1 --policy always --threshold 4096

# casadm -X -n seq-cutoff -i 1 -j 1 -p always -t 4096

Description: Set a cutoff size in KiB to stop the caching of sequential IO reads or writes.

Required parameters:

NOTE: -p and -t parameters aren’t both required. At least one is required.

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

[-p, --policy <POLICY>]: Sequential cutoff policy to be implemented.

Seq-cutoff policies:

always - sequential cutoff is always enabled regardless of cache occupancy; sequential data will not be cached at all after threshold is reached.
full - sequential cutoff is enabled only when the cache is full.
never - sequential cutoff is disabled and will not be triggered; sequential data is handled using current cache policy.

[-t, --threshold <THRESHOLD>]: a value from range 1-4194181 (inclusive). Threshold is expressed in KiB.

Optional parameters:

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>. If not specified, core parameter is set to all cores in a given cache.

[--promotion-count <NUMBER>]: Specify number of IO operations required for the tracking information of a sequential stream to be moved from a per-CPU data structures to the global data structures. This process of moving tracking information to global context is called stream promotion. Once a stream is promoted, CAS will continue recognize its continuation even after application gets migrated to another CPU. If a stream is migrated to another CPU before it gets promoted, it will not be recognized as a continuation and it will be treated as a new stream instead. The lower the promotion threshold, the more synchronization between processors occurs, potentially affecting IO performance. On the other hand, the higher the promotion threshold, the more likely it is for CAS to lose track of sequential stream due to its origin application being moved to another CPU. Recommendation is to set this parameter to value low enough so that an I/O stream is expected to send this many I/O requests before being rescheduled to another CPU.

cleaning

Usage: casadm --set-param --name cleaning --cache-id <CACHE_ID> --policy <POLICY>

Example:

# casadm --set-param --name cleaning --cache-id 1 --policy acp

# casadm -X -n cleaning -i 1 -p acp

Description: This parameter specifies the flushing policy to be used for the applicable cache instance, thus customizing the behavior for flushing dirty data.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

[-p, --policy <POLICY>]: Flushing policy to be used.

Cleaning policies:

acp - (Aggressive Cleaning Policy) Cleans dirty cache lines as fast as possible so as to maintain the highest possible bandwidth to the backend storage, typically HDD’s. ACP is intended to stabilize the timing of write-back mode data flushing and to sustain more consistent cache performance.
alru - (Approximate Least Recently Used) A modified least recently used method that will flush dirty data periodically (default mode).
nop - (No Operation) Disables cache flushing except as needed for cache line replacement.

cleaning-acp

Usage: casadm --set-param --name cleaning-acp --cache-id <CACHE_ID> [--wake-up <NUMBER>] [--flush-max-buffers <NUMBER>]

Example:

# casadm --set-param --name cleaning-acp --cache-id 1 --wake-up 20 --flush-max-buffers 50

# casadm -X -n cleaning-acp -i 1 -w 20 -b 50

Description: This parameter specifies the desired characteristics of the acp flushing policy to be used for the applicable cache instance.

Required parameters:

NOTE: -w and -b parameters aren’t both required. At least one is required.

[-w, --wake-up <NUM>]: Period of time between awakenings of flushing thread in milliseconds. MIN: 0, MAX: 10000 (inclusive), DEFAULT: 10.

[-b, --flush-max-buffers <NUM>]: Number of dirty cache blocks to be flushed in one cleaning cycle. MIN: 1, MAX: 10000 (inclusive), DEFAULT: 128.

cleaning-alru

Usage: casadm --set-param --name cleaning-alru --cache-id <CACHE_ID> [--wake-up <NUMBER>] [--staleness-time <NUMBER>] [--flush-max-buffers <NUMBER>] [--activity-threshold <NUMBER>]

Example:

# casadm --set-param --name cleaning-alru --cache-id 1 --wake-up 30 --staleness-time 120 --flush-max-buffers 50 --activity-threshold 5000

# casadm -X -n cleaning-alru -i 1 -w 30 -s 120 -b 50 -t 5000

Description: This parameter specifies the desired characteristics of the alru flushing policy to be used for the applicable cache instance.

Required parameters:

NOTE: -w, -s, -b, and -t parameters aren’t all required. At least one is required.

[-w, --wake-up <NUM>]: Period of time between awakenings of flushing thread in seconds. MIN: 0, MAX: 3600, DEFAULT: 20.

[-s, --staleness-time <NUM>]: Time that has to pass from the last write operation before a dirty cache block can be scheduled to be flushed in seconds. MIN: 1, MAX: 3600, DEFAULT: 120.

[-b, --flush-max-buffers <NUM>]: Number of dirty cache blocks to be flushed in one cleaning cycle. MIN: 1, MAX: 10000, DEFAULT: 100.

[-t, --activity-threshold <NUM>]: Cache idle time before flushing thread can start in milliseconds. MIN: 0, MAX: 1000000, DEFAULT: 10000.

promotion

Usage: casadm --set-param --name promotion --cache-id <CACHE_ID> --policy

Example:

# casadm --set-param --name promotion --cache-id 1 --policy always

# casadm -X -n promotion -i 1 -p always

Description: This parameter specifies the desired promotion policy of core lines

Required Parameters:

[-p, --policy <POLICY>]: The policy desired for promotion of core lines

Promotion policies:

always - Core lines are attemped to be promoted each time they are accessed.
nhit - Core lines are attemped to be promoted after the n-th access. This n-th access threshold can be set using one of these commands:

casadm –-set-param --name promotion-nhit --cache-id <CACHE_ID> [-o, --trigger] <PERCENTAGE>
Description: Percent of cache to be occupied before cache inserts will be filtered by the policy.

casadm –-set-param –-name promotion-nhit --cache-id <CACHE_ID> [-t, --threshold] <NUMBER>
Description: Number of core line accesses required for it to be inserted into cache. Valid values are from range <2-1000>.

-G | --get-param

Description: This command will retrieve a variety of cache/core parameters which are set via --set-param. See applicable configuration details below.

seq-cutoff

Usage: casadm --get-param --name seq-cutoff --cache-id <CACHE_ID> --core-id <CORE_ID> [--output-format <FORMAT>]

Example:

# casadm --get-param --name seq-cutoff --cache-id 1 --core-id 1 --output-format csv

# casadm -G -n seq-cutoff -i 1 -j 1 -o csv

Description: Allows the ability to obtain current values of seq-cutoff cache/core parameters which are set with --set-param. Parameters that are returned: Sequential Cutoff Threshold and Sequential Cutoff Policy.

Required Parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters:

[-j, --core-id <ID>]: Unique identifier for core <0 to 4095>. Display statistics for a specific core device. If not specified, core parameter is set to all cores in a given cache.

[-o, --output-format <format>]: Sets desired output format for statistics.

table: (default mode) Displays a table of the statistics information.
csv: Outputs a comma separated list of statistics information. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

cleaning

Usage: casadm --get-param --name cleaning --cache-id <CACHE_ID> [--output-format <FORMAT>]

Example:

# casadm --get-param --name cleaning --cache-id 1 --output-format csv

# casadm -G -n cleaning -i 1 -o csv

Description: Allows the ability to obtain current values of cleaning cache/core parameters which are set with --set-param. Parameters that are returned: Cleaning Policy Type.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters:

[-o, --output-format <format>]: Sets desired output format for statistics.

table: (default mode) Displays a table of the statistics information.
csv: Outputs a comma separated list of statistics information. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

cleaning-acp

Usage: casadm --get-param --name cleaning-acp --cache-id <CACHE_ID> [--output-format <FORMAT>]

Example:

# casadm --get-param --name cleaning-acp --cache-id 1 --output-format csv

# casadm -G -n cleaning-acp -i 1 -o csv

Description: Allows the ability to obtain current values of acp cache/core parameters which are set with --set-param. Parameters that are returned: Wake Up Time and Flush Max Buffers.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters:

[-o, --output-format <format>]: Sets desired output format for statistics.

table: (default mode) Displays a table of the statistics information.
csv: Outputs a comma separated list of statistics information. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

cleaning-alru

Usage: casadm --get-param --name cleaning-alru --cache-id <CACHE_ID> [--output-format <FORMAT>]

Example:

# casadm --get-param --name cleaning-alru --cache-id 1 --output-format csv

# casadm -G -n cleaning-alru -i 1 -o csv

Description: Allows the ability to obtain current values of alru cache/core parameters which are set with --set-param. Parameters that are returned: Wake Up Time, Flush Max Buffers, Stale Buffer Time, and Activity Threshold.

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Optional Parameters:

[-o, --output-format <format>]: Sets desired output format for statistics.

table: (default mode) Displays a table of the statistics information.
csv: Outputs a comma separated list of statistics information. This output can be piped to a file and easily parsed or opened in a spreadsheet editor.

promotion

Usage: casadm –-get-param –-name promotion –-cache-id <CACHE_ID>

Example:

# casadm --get-param --name promotion --cache-id 1 --output-format csv

# casadm –G –n promotion –i 1

Description: Retrieves the promotion policy

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

The additional command below can be used to obtain the nhit promotion values for the nhit policy

Usage: casadm –-get-param –-name promotion-nhit –-cache-id <CACHE_ID>

Example:

# casadm --get-param --name promotion-nhit --cache-id 1 --output-format csv

# casadm –G –n promotion-nhit –i 1

Description: Retrieves the nhit promotion policy values

Required parameters:

[-i, --cache-id <ID>]: Unique identifier for cache <1 to 16384>.

Open CAS Linux - Admin Guide

Configuration Tool Details

-S | --start-cache

-T | --stop-cache

-Q | --set-cache-mode

-A | --add-core

-R | --remove-core

--remove-detached

--remove-inactive

-L | --list-caches

-P | --stats

-Z | --reset-counters

-F | --flush-cache

--zero-metadata

-H | --help

-V | --version

-C | --io-class

-C | --load-config

-L | --list

-X | --set-param

seq-cutoff

cleaning

cleaning-acp

cleaning-alru

promotion

-G | --get-param

seq-cutoff

cleaning

cleaning-acp

cleaning-alru

promotion