I'm using freeNAS to share an extent via iSCSI to my another Linux box using Ethernet cable. It work as a block storage. So SAN work as a block storage. Now, in my scenario is it working as a NAS or SAN?

  • Now out of the horse mouth, Using iscsi in freeNAS makes NAS or SAN? Commented Dec 13, 2013 at 12:33
  • I am having trouble comprehending the question. It it a question about what to call it (what type of thing is this, a classification question). Commented Dec 13, 2013 at 12:34
  • What type is that? Commented Dec 13, 2013 at 12:35
  • google search: "iscsi nas or san" = communities.netapp.com/community/netapp-blogs/dave/blog/2007/04/…
    – BitsOfNix
    Commented Dec 13, 2013 at 12:42
  • What type is what? Oh is that question a statement? Commented Dec 13, 2013 at 12:43

2 Answers 2


A NAS is a storage device connected to a network. Its purpose is to serve files to clients using some file sharing protocol like NFS, SMB/CIFS, AFS and the likes.

A SAN is a network interconnecting storage (arrays) to clients. Its purpose is to provide block level access to disk devices (LUNs).

iSCSI is clearly a low level protocol so belongs to the SAN terminology.

The fact it uses ethernet vs fibre-channel doesn't change the fact the high level functionality (eg: file system) is only implemented on the client side.

Of course, modern NAS like the ones based on ZFS are able to provide both file system and iSCSI LUNs at the same time which is likely the reason there is nowadays a confusion between both technologies.

Note also that the border between physical media network protocols is also blurred with infiniband which can be used to transport either TCP/IP (IPoIB), SCSI like (SRP), Sockets (SDP) or raw (RDMA) traffic. In fact, nothing forbids to either encapsulate fibre channel over Ethernet FCoE, fibre channel over IP (FCoIP/FCIP) or even IP over fibre channel (rfc2625)

In any case, it doesn't make sense to refer to iSCSI (= a network protocol) as NAS (= a device).


After doing a deeper research I found the answer to my question:

Mr. Pearson over at IBM just did a post arguing that if you run iSCSI over a dedicated, secure network, then you should call it IP-SAN, but if you run it over a general purpose TCP/IP network then you should call it NAS.

  • Yes, a storage area nework, is a network just for storage. If you use the network for other stuff too you can't just call it a storage network. "Dedicated" is one of the key words in the definition of a san, that it is dedicated to storage. Commented Dec 16, 2013 at 12:10
  • FCoE is for both SAN and Ethernet purpose @BeowulfNode42 Commented Dec 16, 2013 at 12:14
  • I never mentioned FCoE. @Ruban Savvy Commented Dec 16, 2013 at 12:48
  • The link to the presumed original sentence you quoted is broken. The very same Tony Pearson wrote ibm.com/developerworks/community/blogs/InsideSystemStorage/… "Those looking at NAS or iSCSI might consider the IBM System Storage N series products, "unified storage" supporting iSCSI, FCP and NAS protocols. where he clearly doesn't confuse iSCSI and NAS.
    – jlliagre
    Commented Dec 16, 2013 at 22:19

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