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Ciao, I don't understand does SAN device have an operating system? I know it is connected to servers in data center by san switch and it provides data drives to the servers but how the server communicates with the SAN device, how it knows how much data storage it needs to 'take'?

I can't understand this..

Please someone explain.

thanks a lot

Bro Pana
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  • https://en.wikipedia.org/wiki/Storage_area_network *"Ultimately SAN networking and storage devices are available from many vendors. Every SAN vendor has its own management and configuration software"* - so no generic answer is available. As with most technology you would usually call the embedded OS "firmware" rather than using the term "operating system" that implies a more generic multipurpose OS designed to mainly run other applications. – Bob Mar 04 '21 at 12:58
  • I think many, if not most, Fibre Channel or iSCSI disk arrays are actually based on Linux. – berndbausch Mar 05 '21 at 03:19
  • @berndbausch [VxWorks](https://en.wikipedia.org/wiki/VxWorks) is also common. – Andrew Henle Mar 07 '21 at 13:12

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The SAN configuration specifies how to allocate the raw storage space to different user volumes and error correction.

The SAN itself doesn't need a complex operating system, as all it does is shovel data from one side to the other. There is still a minimal system that gives configuration access, but you wouldn't interact with that during normal use.

The servers that use the SAN only have instructions to contact the SAN and provide specific credentials, the SAN then replies with a list of volumes configured for those credentials, including their sizes.

So space isn't "taken" by servers, but rather "given" to them.

The actual communication between the server and the SAN can work in different ways -- the cheapest variant is to use Ethernet and the iSCSI protocol, but there are also dedicated controller cards that have local caches, use a protocol that has lower latency and higher throughput than Ethernet, and provide a BIOS extension to allow booting directly from the SAN without requiring extra mainboard features.

Simon Richter
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