DAS controllers?

[jman22]

Hello again! Quick question for you guys:

Here is something from wiki I overlooked

http://en.wikipedia.org/wiki/Direct-attached_storage

DAS controllers also enable shared storage access, which permits multiple servers (usually no more than 4) to access the same logical storage unit, a feature that is mainly used for clustering. At this point, top range DAS systems share similarities with entry-level SAN systems.

This actually sounds like something I may be interested in. If I understand this correctly (probably not ha), these DAS controllers could allow me to share and access a single storage unit (what is this? a LUN?) between 2 servers. Question is, what are these DAS controllers and where can I find them?

Thanks!
Jared

 

[Chewy509]

Any SCSI or SAS controller that features external connectors is a DAS controller.

All that's needed a drive chassis to house the drives, and a cable(s) to run from the controller to the drive chassis. El' cheapo chassis's expose the individual drives to the controller, with high-end ones let you group drives together in RAID to be exposed as a single SCSI ID/LUN. (This I think is what the article is talking about).

Then you just need to turn off all caching in the OS/Controller, and leave the caching up to the individual drive or chassis controller, if you are sharing a common storage pool between servers/PCs.