Non-flawless software (i.e., 100% of it) is usually dealt with storage snapshots; if they are kept local or remote, that's a design choice that a metro SAN can impact. Doing backup/restores thru a metro SAN also has some advantages on facilities with tight-controlled physical access; the bandwagon that moves tapes to off-site storage still has more bandwidth than the fiber, but it can also be used to smuggle <insert-your-favorite-paranoia-here>. Rubens ----- Original Message ----- From: "Petri Helenius" <pete@he.iki.fi> To: "Gordon Cook" <cook@cookreport.com> Cc: <Nanog@merit.edu> Sent: Monday, May 19, 2003 7:33 AM Subject: Re: An area for operations growth - Storage Area Nets in MANS | | | Although I agree that storage networking as a backup/tandem resiliency | operation makes a lot of sense, | it does not come anywhere nearly "free" because the assumptions made | there require flawless software. | If you always synchronize your systems you'll also blow them both out | when you hit a software issue | and as most of the audience is painfully aware, they are not infrequent | enough to count out of the equation. | | So you need to keep track how to re-synchornize after an | upgrade/failure/etc. With a large stream of | updated data on the system keeping the state difference becomes | expensive quickly. (unless you are going | to re-sync everything after a failure, and then you'll be vulnerable | until that's completed) | | Pointers to perfect SAN solutions appreciated. | | Pete | | | Gordon Cook wrote: | | > | > Roxane Googin is usually ahead of the competition in spotting trends | > in data net use. here is what has has to say about enterprise use of | > MANs. | > | > | > COOK Report: Where are the metro area networks going? | > | > Googin: Probably the killer application for the MAN is grid computing | > and storage area networks. A lot of people think the driver for | > broadband access to the home is going to be multi-media. People, when | > they think about next generation networks, think home use. But this | > is never where the money has been. And no phone company is ever going | > to build the infrastructure. | > | > Although these new real time applica tions will clearly send more data | > over the network, the real killer application is going to be remote | > storage and synchronous storage. Synchronous storage means that you | > have two large servers doing the exact same thing at the exact same | > time in two different locations. | > | > COOK Report: Like a decentralized disk array? | > | > Googin: Yes. The backbone has to be incredibly fast because you | > cannot complete a transaction until you have acknowledgments from both | > disk drives. This will happen. Probably this year. What they are | > already doing is taking fiber channel and putting that on a Cienna | > Core Director optical switch port. Half of the ports being sold on | > the Core Director now are fiber channel. They aren't even Ethernet. | > And this is used for storage area nets (SANs). These are corporate | > MANs and will have nothing to do with sales to service providers. | > They are bypass business services where the storage arrays may not be | > more than a kilometer or two apart. These SANs are backing up | > continuously terabytes of data. We are talking huge applications that | > will use every bit of access to every bit of capacity they can get. | > | > COOK Report: Is 9/11 a motivation for this? | > | > Googin: Partly. Not only that but the whole paradigm of the real time | > organization will drive it. It used to be that your server had its | > own storage. It was a "stove pipe" connected to the CPU. Now as soon | > as you decouple that "stove pipe," you can put it anywhere. What they | > are finding is that if they have two of them that are mirrored in real | > time and place remotely that they do not have to do as much management | > of resources. | > | > COOK Report: Then forget the disaster back up and recovery | > operations? Those are the next to be marked for extinction? | > | > Googin: Oh yes. It is so elegant. The new architecture cannot be | > supported on direct attached storage. It must move off the server and | > it is doing so. If you have to go through a server to get to the | > storage, it simply doesn't work. Storage can't become just a utility | > until you move it off the server. The MAN will be backing up | > terabytes of data regularly and in real time. Disaster recovery, in | > real time, comes for "free". | > | > For more detail please see | > | > Fiber & Wireless as First Mile Technology - Fiber Business Models & | > Architecture http://cookreport.com/12.04-06.shtml | | |