[avahi] avahi for storage services?

Iván Sánchez Ortega i.sanchez at mirame.net
Sun Feb 19 09:40:19 PST 2006

Hash: SHA1

El Domingo 19 de Febrero de 2006 17:40, Bruce Edge escribió:
> Do SANs and other storage services, like iSCSI, fall under the intended
> scope of avahi?

Avahi is a DNS service discovery system, and a mDNS responder (announcer). It 
is not a storage techonology, that's for sure.

I think your question should be rephrased into:

Can I use Avahi to announce and/or browse SANs and other storage devices?

Answer: you can use Avahi (and whatever other implementation of DNS-DS) to 
announce and/or browse any service that is covered in the DNS SRV (RFC 2782) 
Service Types list. Please have a look at 
http://www.dns-sd.org/ServiceTypes.html . Of course, you can add any other 
services to that list.

Also, remember what's the purpose of DNS Service Discovery. Your computer 
shouts "Is anybody out there??", and gizmos in the network reply "Hi there, 
I'm, and I'm a HTTP and FTP server".

This would make sense, but there is a problem: the iSCSI specifications 
include a method for target discovery, as noted in RFC 3720, appendix D 
(http://www.ietf.org/rfc/rfc3720.txt). I'm going to put my conservative hat 
and tell you "If it works, don't touch it". iSCSI has its own method to 
discover targets, leave it alone.

However, if I put my lets-have-some-fun hat, I'd replace the entire 
SendTargets request mechanism with a multicast DNS service discovery system 
(Avahi/Bonjour/whatever). But, this could prove troublesome (as the iSCSI 
devices should support both the SendTargets and mDNS announcements) and 
somewhat incompatible (some clients/devices that only support one of 

IMHO, replacing the iSCSI discovery method with Avahi is not a very good (and 
backwards-compatible) idea.
However, if your storage devices offer any other methods for accesing the data 
(HTTP/FTP/rsync/NFS)... what are you waiting for to use Avahi to announce and 
discover them??!

P.S.: I have read RFC3720 very, very briefly. Oh, and don't take me too 

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Iván Sánchez Ortega <ivansanchez at escomposlinux.org> <i.sanchez at mirame.net>

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