"Eddy Harvey" <[EMAIL PROTECTED]> wrote: > SAN is faster and better, but more expensive.
We could debate which is faster and why but let's not. I will, however, argue with "better": NAS and SAN -- or more correctly, file sharing versus block access -- serve two different purposes and most often solve different problems. If your requirement is to give multiple hosts read/write access to the same file while preserving locking semantics and the like, block access is almost certainly worse than file access and, in particular, than a file *sharing* protocol such as NFS or CIFS. > . . . 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. I will match my NetApp NFS server against any SAN box and show you as good if not better numbers for speed and reliability. I will also match my high-end Cisco plain old Ethernet switch against any Fiber Channel switch for reliability and again get as good if not better numbers. As for hanging the system, well, NFS might or might not hang but the system won't necessarily crash. When you SAN switch or network dies, it's like ripping the system disk out from under a running system -- you *will* crash. My point is that, in general, reliability is far more about what hardware you choose and how you connect it up than the protocol and/or access method the hardware provides. > More Expensive: I normally expect a SAN to cost at least 3 times more > than NAS of the same size. While I will be the first to admit that a NFS setup from NetApp is one of the most expensive you can find, it's often less that "equivalent" SAN set-ups. But the great thing is that same hardware can provide SAN service, too (at the same time, no less), so you can build a very reliable SAN for roughly the same cost as a NAS set-up. Well, provided you use iSCSI and not FC, 'cause FC switches are always gonna drive the cost up. AdamM _______________________________________________ bblisa mailing list [email protected] http://www.bblisa.org/mailman/listinfo/bblisa
