[luau] SANs

[Charles Lockhart]

Thanks Brian,

Question, as I understand it, these arrays are typically set to RAID-0 for
striping across the drives, thereby increasing throughput.  Assuming this
is correct, do you know how many drives are required, or typically
required, for this?

-Charles

On Tue, 4 Jun 2002, Brian Chee wrote:

> Hmmmm.....let's see how well this can be done in a nutshell....
> 
> SAN's come in several flavors, but the idea is that from a 64bit cards
> (yup...if you ain't got 64bit PCI slots, you're not going to get anything
> better than ultra160) you travel over a fiber optic path to either a switch
> or a hub.  Just like data networks a switch is a good idea if you have a
> multipath environment with multiple destinations....if you have but one
> server with one set of drives...then a switch is not necessary....a single
> HBA (fiber channel comes 1mb/sec or 2mb/sec) to an elcheapo hub to the jbod
> (just a bunch of disks) is pretty inexpensive and gives you the terrific
> throughput that folks like about sans.
> 
> Now iscsi and such....same thing with a different name, different protocol
> with different amounts of overhead, etc....keep in mind that if you wanna
> play your storage over IP...that you're paying for the IP
> overhead....1gb/sec fiberchannel is faster than storage over Gig-ethernet
> due to overhead.
> 
> Linux is supported well by qlogic and compaq is a relabeled qlogic card (may
> have changed...heard rumblings about emulex too).....interphase had great
> cards (gib+fiber channel) but I'm not sure they're around anymore????
> 
> I've run qlogic cards in solaris, linux and NT...they all work well....but a
> switch is necessary only if you're mixing several systems and have to carve
> up your array into several pieces.....but if only one system and one set of
> drives (can be multiple jbods) then a hub is fine.  Emulex makes fine cards
> and hubs....
> 
> Oh yeah....most fiber channel doodads are LC fiber connectors over multimode
> fiber....those suckers are VERY expensive cables....you can also do sans
> over copper which is LOTS cheaper, just change the gbic....oh yeah, a
> gigabit ethernet SX fiber gbic is exactly the same at layer1 as fiber
> channel 1gig.....they are interchangable....
> 
> /brian chee
> 
> University of Hawaii ICS Dept
> Advanced Network Computing Lab
> 1680 East West Road, POST rm 311
> Honolulu, HI  96822
> 808-956-5797 voice, 808-956-5175 fax
>