Managing the Media Cache

The media caches/disks are active and enabled by default and typically require no configuring. However, you must deactivate and/or disable disks and caching to change disks. Before you activate or enable a cache, run show media-cache disk list and get the name assigned to the disk to use in configuration. See media-cache for CLI details.

In Release 2.0.2 Media Flow Controller supports 3 cache tiers corresponding to SSD (tier 1), SAS HDD (tier 2), and SATA HDD (tier 3). "Hot" content generally stays in tier1 (the highest). Media Flow Controller promotes contents between the cache tiers based on content hotness (see ““Hot” Content (Short Tail vs. Long Tail)” on page 29 for definition). As content gets hotter, it is promoted to the next higher tier. 1st time content is always put in the lowest cache tier. The default values are: tier1 weight = 6, tier2 weight = 2, tier3 weight = 1. So, any content requested once is cached in Tier 3; requested twice and it is promoted to Tier2; and, if requested 6 times, it is promoted to Tier1. Example:

show media-cache disk list

Device Type Tier Active Cache Free Space State

------ ---- ---- ------ ----- ---------- -----

dc_1 SATA Tier-3 yes yes 38890 MiB cache running

dc_2 SATA Tier-3 yes yes 68668 MiB cache running

Total Free Space: 107486 MiB

1.	Get system-assigned disk names to use in configuration. Use list to view all disk drives, their names, physical location, serial number, type, and capacity. Use cache_name to view information on the specified cache.

show media-cache disk {list |<cache_name>}

show media-cache disk list

Example:

test-vos (config) # show media-cache disk list

show media-cache disk list

Device Type Tier Active Cache Free Space State

------ ---- ---- ------ ----- ---------- -----

dc_1 SATA Tier-3 yes yes 38890 MiB cache running

dc_2 SATA Tier-3 yes yes 68668 MiB cache running

Total Free Space: 107486 MiB

2.	Determine the free block thresholds of the disk caches.

show media-cache free-block threshold

3.	Disable a disk if you need to pull the disk for any maintenance purposes; for example, to upgrade to a higher capacity disk, replace a SATA disk with a SAS disk, replace a failed disk, reformat the disk, or if contents should not be cached.

media-cache disk <cache_name> cache disable

4.	Deactivate a disk cache. Media Flow Controller allows OIR (On-line Insertion and Removal) of HDD (Hard Disk Drives). However, the HDD MUST be made inactive to be removed. When a new HDD is in the disk, it must be made active and (if so decided) enabled for caching.

media-cache disk <cache_name> status inactive

5.	Pull the drive, put in a new drive, and mount the new disk.

media-cache disk mount-new

6.	Find the inactive disk’s name.

show media-cache disk list

7.	Activate or re-activate a media-cache.

media-cache disk <cache_name> status active

8.	Format the disk if it is newly inserted and empty and/or you do not want to use its contents. Do this after you issue the mount command.

media-cache disk <cache_name> format

9.	Enable or re-enable a disk for caching.

media-cache disk <cache_name> cache enable

Example:

test-vos (config) # show media-cache disk list

Device Type Tier Active Cache Free Space State

------ ---- ---- ------ ----- ---------- -----

dc_1 SATA Tier-3 yes yes 38890 MiB cache running

dc_2 SATA Tier-3 yes yes 68668 MiB cache running

Total Free Space: 107486 MiB

test-vos (config) # media-cache disk dc_2 cache disable

Disk Cache Disabled

test-vos (config) # media-cache disk dc_2 status inactive

Disk Deactivated

test-vos (config) # media-cache disk mount-new

Message sent to detect for new disks

Please check disk state for status

test-vos (config) # show media-cache disk list

Device Type Tier Active Cache Free Space State

------ ---- ---- ------ ----- ---------- -----

dc_1 SATA Tier-3 yes yes 38890 MiB cache running

dc_2 SATA Tier-3 no no - disk has been deac tivated

Total Free Space: 107486 MiB

test-vos (config) # media-cache disk dc_2 status active

Disk Activated

test-vos (config) # media-cache disk dc_2 format

Disk Formatted

test-vos (config) # media-cache disk dc_2 cache enable

Disk Cache Enabled

test-vos (config) # show media-cache disk list

Device Type Tier Active Cache Free Space State

------ ---- ---- ------ ----- ---------- -----

dc_1 SATA Tier-3 yes yes 38890 MiB cache running

dc_2 SATA Tier-3 yes yes 68668 MiB cache running

Total Free Space: 107486 MiB

To make these configurations using the Management Console, go to the Service Config tab, Media-Cache page; see Service Config > Media-Cache for details.