Explain please what is mean Mapped and Remote

[kaltura]

Explain please what is mean Mapped and Remote

[erankor]

Mapped mode probably won't help, to clarify regarding the different modes, the choice of modes is usually:

1. If you don't have the mp4 files locally, then you use remote mode, an example of such a scenario is a CDN working in origin-pull mode
2. If you have the files and you don't need any custom logic to map the playback URL to the mp4 file path, use local mode
3. Otherwise, if you want to have some remote server decide on the file path of the mp4 that should be used for a certain request, use mapped mode

Back to your problem, it's hard for me to provide specific guidelines without a full understanding of the setup or the ability to debug it, but I can provide the following generic performance guidelines for using nginx-vod-module:

1. Unless you have a small scale deployment, don't have users play the videos directly from nginx-vod-module - for medium scale add a layer of caching proxies between the vod module and the end users (can use standard nginx servers with proxy_pass & proxy_cache). For large scale deployments, I would recommend using a CDN (such as Akamai, Level3 etc.). Since all the different streaming protocols supported by nginx vod are HTTP based, they can be cached by standard HTTP proxies / CDNs. Also, in general, it's best to have nginx vod as close as possible to where the mp4 files are stored, and have the caching proxies as close as possible to the end users.
2. Enable caches on the nginx-vod server:
   a. vod_moov_cache - saves the need to re-read the video metadata for each segment. This cache should be rather large, we currently use 4GB and we get about 90% hit ratio.
   b. vod_response_cache - saves the responses of manifest requests, may not be required if you have a second layer of caching servers before nginx vod. This cache does not to be too large, 128M is probably more than enough for most deployments.
   c. vod_path_mapping_cache - for mapped mode only, few MBs is usually enough
   d. nginx's open_file_cache - caches open file handles
   You can check the effectiveness of these caches by enabling performance counters (vod_performance_counters) and setting up a status page for nginx vod (vod_status)
3. In local & mapped modes, enable aio. Support for aio has to be compiled to nginx, and it then has to be enabled in nginx conf (aio on). You can verify it works by looking at the performance counters on the vod status page - read_file vs. async_read_file
4. In local & mapped modes, enable asynchronous file open - nginx has to be compiled with threads support and then vod_open_file_thread_pool has to be specified. You can verify it works by looking at the performance counters on the vod status page - open_file vs. async_open_file
5. Enable gzip compression on manifest responses - gzip_types application/vnd.apple.mpegurl video/f4m application/dash+xml text/xml
6. Apply common nginx performance best practices, such as tcp_nodelay=on, client_header_timeout etc.

Hope this helps

[kaltura-hooks]

Hi @sergiyshutov,

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[erankor]

Local = the mp4 is read from a file, can be either local disk or some NFS mount. When working with NFS it is highly recommended to use asynchronous I/O (nginx has to be compiled with aio support and it also has to be enabled in nginx.conf)
Remote = the mp4 is fetched using HTTP range requests from some remote server. Note that the full video metadata (=mp4 moov atom) is required for every request, so it is highly recommended to configure a large enough moov cache (vod_moov_cache). In the case of video/audio frame data, on the other hand, only the minimum subset that is relevant to the specific segment is fetched.
Mapped = the mp4 is read from a file (like Local), but a remote server performs the mapping between the request URI and the actual file path. So, nginx-vod-module initially performs an HTTP request to some upstream, gets a file path in response, and continues with the flow of local mode using the path received from the remote server.

Regarding load balancing, it's not part of this module, on our production environment, for example, we have several nginx servers running nginx-vod-module in mapped mode and serving files from a shared NFS storage. These servers are behind an F5/Big Ip load balancer.

In storage server i need use Local mode and other server Mapped?
Can you please give example config with mapped mode.
Thanks :)

Sorry. Can you please give example nginx config in storage server and Mapped server? I mean how to use this between 2 and more servers :)

Because i have problematic situation right now. I have one server in hetzner 16gb ram, port 1gb (200 mbps guaranteed). Nginx installed with vod module and https://github.com/vozlt/nginx-module-vts. In status page i have this: active connections: 500, reg per second 40-60, and server start lag. So, what i need to make? one more storage server or i can play with mapped mode or something like that?
Thank you very much :)