[BBLISA] iSCSI - opinions / experiences?

[Eddy Harvey]

I think you mean to compare ...

NAS vs SAN.  Right?   Not nfs vs iscsi.

It just so happens that nfs is one protocol that can be used to build NAS.
And it just so happens that iscsi is one protocol that can be used to build
SAN.

NAS is basically file sharing over a network, such as nfs or cifs.

SAN uses a specialized set of hardware and drivers to make a disk appear
local to the OS, even though the disk is on the other end of some kind of
network (usually a fiber brocade switch).  A SAN disk can be used
simultaneously by more than one computer.

SAN is faster and better, but more expensive.  What do I mean by that?  
Faster:  Using a bus that's the same speed (probably 1GB) you have much less
overhead than nfs, and more dedicated pathway.  So you have lower latency
and higher sustainable throughput.  Put simply, SAN tends to be around twice
as fast as NAS, given the same speed hardware.
Better:  Since the disk appears to be locally attached, you can
mount/unmount as if it were a local disk.  You can boot from it (if you have
the right drivers and whatnot).  And in my personal experience, nfs has a
tendency to hang up the system whenever there's a network outage or you
reboot the nfs server.  You don't have that problem with SAN, because the
network is more reliable and there is no nfs server.
More Expensive:  I normally expect a SAN to cost at least 3 times more than
NAS of the same size.




> -----Original Message-----
> From: bblisa-bounces at bblisa.org 
> [mailto:bblisa-bounces at bblisa.org] On Behalf Of Steve Revilak
> Sent: Thursday, June 15, 2006 8:48 AM
> To: bblisa at bblisa.org
> Subject: [BBLISA] iSCSI - opinions / experiences?
> 
> At my workplace, we have several shared filesystems (a 
> combination of NFS and samba/CIFS).  They're adequate, but 
> not without some level of headaches and hassles. (Fedora NFS 
> being a particularly bad headache).
> 
> I've been starting to look at iSCSI as an alternative.  I 
> guess my biggest question is whether it's a viable 
> alternative for NFS/CIFS.
> I'm also curious as to how well it handles types of work that 
> are traditionally reserved for `local disks' (eg - 
> applications that need reliable file locking).
> 
> Have any of you had experience with iSCSI?
> 
> 
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