capacity for MediaSense is a function of the hardware profile that the system
selects at startup time. The hardware profile depends on which VM template the
node is deployed on, and the VM template depends partially on what type of
hardware you are deploying. (See "Virtual machine configuration" for a full
description of each template.) The "Hardware profiles" section below shows the
actual capacity when using each type of VM template.
For example, for
each "7 vCPU" template node (the standard for large production deployments) the
MediaSense server supports up to 400 media streams simultaneously (200 calls)
at a sustained busy hour call arrival rate of two calls per second on up to 12
terabytes of disk space. The 400 represents all streams used for recording,
live monitoring, playback, .mp4 or .wav conversion, and HTTP download; all of
which may occur in any combination. Conversion and download are not strictly
speaking streaming activities, but they do use system resources in a similar
way and are considered to have equal weight. Playback of a video track takes 9
times more resources than playback of an audio track. As a result, each
uploaded video playback (one video track + one audio track) has the weight of
10 audio tracks, leading to a maximum capacity of 40 simultaneous video
playbacks per node.
In determining how
many streams are in use at any given time, you need to predict the number of
onsets for each activity per unit time as well as their durations. Recording,
live monitoring, and playback have a duration that is equal to the length of
the recording. Video playbacks, if configured to play once only, have a
duration equal to the length of the video. Video playbacks for hold purposes
must be estimated to last as long as each video caller typically remains on
hold. The .mp4 conversions, .wav conversions, and HTTP download durations are
estimated at about 5 seconds per minute of recording.
To determine the
number of servers required, evaluate
the number simultaneous
audio streams needed plus 10 times the number of videos being played, divided
by the number of audio-weight media streams supported by each node
the number of busy hour
call arrivals divided by the maximum call arrival rate for each node
the space required for
retained recording sessions divided by the maximum media storage for each node.
The number of
servers required is equal to the largest of the above three evaluations
Video playback for
VoH, ViQ, and Video Messaging is further limited on 2\- and 4-vCPU virtual
hardware and depends on the type of physical hardware being used. See the
section for details.
that significantly impacts performance is the number of MediaSense API requests
in progress. This is limited to 15 at a time for 7-vCPU systems, with the
capability to queue up to 10 more (the figures are reduced for smaller
systems). These numbers are per node, but they can be doubled for MediaSense
clusters that contain both a primary and a secondary node. For more
information, see "System resiliency and overload throttling".
The media output
and conversion operations (monitoring, playback, convert to MP4 or WAV, and
HTTP download) are entirely under client control. The client enforces its own
limits in these areas. The remaining operations (call recording and uploaded
media file playback) are not under client control. The deployment can be sized
so that the overall recording and video playback load will not exceed a desired
maximum number cluster-wide (leaving room for an enforceable number of
monitoring, playback, and HTTP download operations). The recording and video
playback load is balanced across all servers. (Perfect balance will not always
be achieved, but each server has enough room to accommodate most disparities.)
nodes are installed, they adjust their capacity expectations according to the
hardware resources they discover from the underlying virtual machine. When the
server is installed using one of the Cisco-provided OVA templates, the correct
amount of CPU and memory are automatically provisioned and a matching hardware
profile will be selected. The hardware profile determines:
the number of
audio-equivalent calls supported,
the number of
concurrent API requests supported,
call arrival rate supported,
number of nodes supported in the cluster,
amount of media storage available,
the cap on
number of video playbacks supported, and
a number of
other internal parameters
as a function of
the number of vCPUs, CPU speed, and amount of memory provisioned.
If an incorrect
OVA template is used, or if the virtual machine's configuration is changed
after the OVA template is applied such that the virtual machine does not
exactly match one of the existing hardware profiles, the server is considered
to be unsupported and the capacities in the "Unsupported" category are used.
record calls that are up to eight hours in duration. Beyond that duration, some
sessions may end up being closed with an error status and HTTP download and
.mp4 or .wav conversion functions may not succeed.
MediaSense uses storage for two distinct purposes. One set of disks
holds the operating software and databases, and the other set is used for media
storage. The two kinds of storage have very different performance and capacity
requirements. Thin provisioning is not supported for any MediaSense disks.
Recorded Media Storage. Up to 60 terabytes is supported per
cluster, divided into 12TB in each of five servers. This is the theoretical
maximum, which could only be attained if you are using SAN storage. If you are
using Directly Attached Disks (DAS), then you are limited to the physical space
available in the server.
Uploaded Media Storage. Uploaded media requires much less
storage, but can also support up to 60 terabytes, divided into 12TB in each of
If you are using Directly Attached Disks (DAS), then the first two
disks (for operating software and database) must be configured as RAID 10.
If you are using SAN, note that only fiber-channel attached SAN is
supported, and the SAN must be selected according to Cisco's specifications for
supported SAN products (see "Cisco Unified Communications on the Cisco Unified
Computing System" at
http://www.cisco.com/go/swonly). Also, SAN storage must
be engineered to meet or exceed the disk performance specifications for each
MediaSense virtual machine. These specifications are per node. If the nodes are
sharing the same SAN, then the SAN must be engineered to support these
specifications, times the number of nodes. For security purposes, it is
permissible to use an encrypted SAN for media storage as long as the
specifications at the link below can still be met.
UCS-E router blade modules come with fixed disk hardware and
MediaSense scalability limits for each type of module are designed with their
actual performance characteristics in mind. You do not need to engineer their
disk arrays to meet the specifications above. However, all of the drives should
be manually configured as RAID-1.
Also, for these modules, the required downloadable .OVA template
automatically carves the disks into two 80GB drives and one 210GB drive,
formatted. For those modules that have additional disk space available, you may
configure the additional space for either uploaded media or recorded media as
best suits your application.
Unified Border Element
A Cisco 3945E ISR
G2 router, when running as a border element and supporting simple call flows,
has a capacity of about 1000 simultaneous calls (if equipped with at least 2
GB—preferably 4 GB of memory). In many circumstances, with multiple call
movements, the capacity will be lower—in the range of 800 calls (due to the
additional signaling overhead). In addition, the capacity will further be
reduced when other ISR G2 functions (such as QoS, SNMP polling, or T1 based
routing) are enabled.
will need to deploy multiple ISR G2 routers in order to handle the required
call capacity. A single MediaSense cluster can handle recordings from any
number of ISR G2 routers.
The above applies to both Unified Border Element dial peer recording and Unified Communications Manager Network-Based Recording.
Network Bandwidth Provisioning
For Call Recording
If Call Admission Control (CAC) is enabled, Unified Communications Manager
automatically estimates whether there is enough available bandwidth
between the forking device and the recording server so that media
quality for either the current recording or for any other media
channel along that path is not impacted. If sufficient bandwidth
does not appear to be available, then Unified Communications Manager does not record
the call; however, the call itself does not get dropped. There is
also no alarm raised in this scenario. The only way to determine
why a call did not get recorded in this situation is to examine its
logs and CDR records.
It is important to provision enough bandwidth so that this does
not happen. In calculating the requirements, the Unified Communications Manager
administrator must include enough bandwidth for 2 two-way
media streams, even though the reverse direction of each
stream is not actually being used.
Bandwidth requirements also depend on the codecs in use and, in
the case of video, on the frame rate, resolution, and dimensions of
For Video Playback
Media connection negotiation is still bi-directional for video playback (even though MediaSense only sends data and does not receive it). This is an important
consideration since the
use of bi-directional media implies that you must
provision double the bandwidth than what you might have otherwise
Impact on Unified Communications Manager Sizing
MediaSense does not connect to any CTI engines, so the CTI
scalability of Unified Communications Manager is not impacted. However, when
MediaSense uses Cisco IP phone built-in-bridge recording, the
Unified Communications Manager BHCA increases by 2 additional calls for each concurrent
For example, if the device busy hour call rate is six (6)
without recording, then the BHCA with automatic recording enabled
would be 18. To determine device BHCA with recording enabled, use