How Wowza Engine Server cache Chunks on RAM

Wowza Streaming Engine
1

Hi everyone,

I know that with Live Stream Application, Wowza Engine server cache some chunks on RAM, with the number is “MaxChunkCount”.

How about VoD Application ?

Does it cache VoD chunks on RAM?

If Wowza Engine Server cache VoD chunks on RAM and two user request for a same VoD concurrently, does they use the same RAM location?

Thank you.

2

Hi,

Wowza only hold chunks for HTTP clients in memory for live streams.

You may have noticed in the packetization articles, there is no option to change MaxChunkCount for video on demand.

Jason

3

Hi,

Does it mean everytime user request for a VoD content, the Wowza Engine Server access to storage to get the content?

Yes, when using a standard VOD application it will read the file from the content directory for each client as required.

Because my Wowza Server cache VoD on SAN. I use iSCSI to connect my Wowza Engine Server to SSD Storage on SAN.

Using Caching to save Bandwidth is still efficient, isn’t it?

If caching local to the destination then yes it should be more efficient than fetching it from the source if it lives across the wire.

Jason

4

Hi JasonH,

Does it mean everytime user request for a VoD content, the Wowza Engine Server access to storage to get the content?

Because my Wowza Server cache VoD on SAN. I use iSCSI to connect my Wowza Engine Server to SSD Storage on SAN.

Using Caching to save Bandwidth is still efficient, isn’t it?

Thank you.

5

Hi @Jason_Hilton

Could you tell us why Wowza don’t hold chunks in memory for vod?
By the way, I’m using Media Cache to connect S3 source. I would like to confirm that Media Cache doesn’t cache chunks in memory, right?
Is there any way to cache chunks in memory for vod with Wowza?

6

Hi,
The Wowza Streaming Engine software creates the chunks on the fly using the on-demand content so it doesn’t need to cache the data in memory as it’s already instantly available.

The MediaCache functionality will get the data from the MediaCache Source (in this case S3) in segments which are cached on the machine where the Wowza Streaming Engine software is installed but they’re written to disk and not stored in memory.

The MediaCache functionality allows a large about of files to be available while using fast disk(s) or SSD(s) on the Wowza Streaming Engine side to deliver this content to your viewers without filling them as only the content that’s been recently viewed will be cached.

Regards,
Jason Hilton
Technical Support Engineer
Wowza Media Systems