An Online Video Placement Policy based on Bandwidth to Space Ratio (BSR) by Asit Dan and Dinkar...

An Online Video Placement Policy based on Bandwidth to Space Ratio (BSR)

by Asit Dan and Dinkar Sitaram

IBM T.J. Watson Research Center

Agenda

Background Aim Implementation Details Simulation Result Difficulty

Background

Video Server contain several storage devices Each storage device has different storage and

bandwidth Each video has different popularity and it change

continuously Each video has different file size and play back bit rate Popular movie: multiple replicas created on multiple

storage devices

Aim

Balance the load Make the best use of bandwidth and space of

the storage device

Implementation Details

First Phase

Determines whether additional replicas are necessary

(Additional expected load > free bandwidth of the devices on which the replicas reside)


Device 1

Bandwidth: 10unit

For Example

Originally movie 1’s demand is 5 unit.

Device 1 contain movie 1

After some time,

Movie 1’s demand change to 11 unit

New replica are needed


Second Phase: Selection of devices

BSR of the video objects on a device =

Total allocated bandwidth

Total allocated Space


For example, device 1 contain two movies,

BSR of video object on device 1 = (B+C)/(E+F)

Free D

Allocated for movie 1E

bandwidth space

Allocated for movie 2F

Free A

Allocated for movie 1B

Allocated for movie 2C


BSR deviation of a device:

Deviation of the BSR of the video object in device from the BSR of that device

BSR deviation of device 1 = |(A+B+C)/(D+E+F) –

(B+C)/(E+F)|


For each device without this movie,1. Sort device with BSR deviation in decreasing order2. Place the movie in the device if BSR deviation of the

device can be reduced3. Loop break if additional expected load can be

satisfied

If the load cannot be satisfy, constraint 2 are ignore and run the loop again


Third Phase: Reallocate the expected load

Allocate the expected load over all replicas, in order to minimize the BSR deviation of the devices


8

2

5

5 8

2 5

5

BSR deviation of device 1 = |8/5 – 10/10| = 3/5

BSR deviation of device 2 = |2/5 – 10/10| = 3/5

Device 1 Device 2

Bandwidth BandwidthSpace Space

Allocated

Free


5

5

5

5


5

5

5

5

BSR deviation of device 1 = |5/5 – 10/10| = 0

BSR deviation of device 2 = |5/5 – 10/10| = 0

After reallocation:


Forth Phase: Consolidation

Execute only if phase 2 failed

Try to decrease the replica of other movie, in order to save space and accommodate the new replicas


For example: place a new replica of movie 2(load : 9, space : 5)

9

1

5

5

Device 1 Device 2


Allocated for movie 1

Free

9

1

5

5


5

5

Device 1 Device 2


Allocated for movie 1

Free

9

1

10Allocated for movie 2

9

1

Simulation Results

The expected load of video are in Zipf distribution

Place the video into the system The system is unable to accommodate all

video(stress test) Test for four different configurations

Simulation Results

Each configuration contain 4 storage device Total Bandwidth of all configurations are the

same Total Storage of all configurations are the

same

Simulation Results

(bandwidth,storage)

Device1 Device2 Device3 Device4

Config1 (x,y) (x,y) (x,y) (x,y)

Config2 (0.8x,y) (0.9x,y) (1.1x,y) (1.2x,y)

Config3 (0.6x,y) (0.8x,y) (1.2x,y) (1.4x,y)

Config4 (0.6x,1.2y)

(0.8x,1.1y)

(1.2x,0.9y)

(1.4x,0.8y)

Simulation Results

Simulation Results

popularity

Video index

Difficulty

Difficult to predict the expected load in the next moment accurately

Wrong Prediction has high impact on the performance of the placement policy

An Online Video Placement Policy based on Bandwidth to Space Ratio (BSR) by Asit Dan and Dinkar...

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