On Tue, 29 Aug 2000, rolyaT yuG wrote:
> Can anybody give me a simple breakdown of how SANS work...
The term "Storage Area Network" means different things to different people.
In general it means a large amount of storage (typically 0.5 terabytes
minimum) with reliability and redundency capabilities.
The current leader in this field is a company called EMC. EMC put a lot of
smarts into their storage towers. These towers have more than one power
supply and a bunch of microcontrollers. The microcontrollers worry about
things like RAID, making sure the file system is in a useable state if the
power goes off (so Unix systems don't have to fsck the disks upon reboot)
and abstract the disks to allow NT and Unix boxes to access the towers.
Typically you attach one or more servers to the same tower. EMC claim that
because the towers have multiple buses there is not much disk access
contention.
Another interesting feature of the EMC towers is that the towers can mirror
themselves to other towers in a different location. This is useful for
companies like banks that have an "offsite" backup for emergency situations.
It also means that you don't have to worry about things like database
replication because the towers in this configuration take care of it for you.
Note, however, this type of mirroring is one way only.
Hope this doesn't sound too much like an ad for EMC. Sun and IBM are also
trying to get into this field in a big way at the moment, but their offerings
are much "dumber" than EMCs (but sometimes simplicity is an advantage).
Semper Fi.
Rob.
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