Why should one use SAN instead of local hard disk? I am really a novice in hardware configuration.
Some of the answers were great:
My favorite (written by Matt Whitfield):
- Performance. Most SANs allow you to attach extra shelves to the array, thereby giving you an easy way to up performance by throwing spindles at it.
- Scalability. Same reason again, more spindles = more space, as well as more performance.
- Redundancy. Using a SAN puts your data on a separate physical entity. SANs generally offer the facility for redundant controllers, fabric connections and power supplies. That way you can connect the SAN to multiple servers over a totally redundant fabric to achieve full redundancy. That fabric might be fibre channel, or it might be iSCSI, but either way, it’s the redundant part that counts.
- Maintenance. When a disk dies (which it will), then on a SAN you just pop out the old disk, and pop in the new. If you have been sensible enough to assign a hot-swap spare or two, then one of those will have already caught up with the array, and the disk you put in will become the new hot-swap spare.
- Flashing lights. People who look round data centres are typically impressed by flashing lights, and SANs tend to have a lot of them.
That summarized a lot of major points (flashing lights especially :)), but it’s missing a few details:
- No mention of Automated Data Placement type features which leverage Flash drives – EMC’s Fully Automated Storage Tiering is an example of this
- No mention of advanced protection functionality like replication and space-efficient snapshots
- No mention of virtualization awareness and integration (Hyper-V and VMware)
- No mention of dynamic capacity management functionality – i.e. thin provisioning
I helped write a recent Top 5 Reasons Why EMC Unified Storage for SQL Server document – and I think we did a great job capturing a lot of these details without too many words – and used some really talented graphic designers to turn my stick figures and chicken scratch into works of art.
Check it out!