Wednesday, September 24, 2014

storage area network - How do I connect a disk array?




I am just starting out with servers and was recently given an IBM DS3200. It is my understanding that this is a disk array, which is just storage that can be attached to a SAN. Am I correct in that understanding? What is the difference between it and a SAN? Do I need a SAN to be able to use the DS3200? I know all these questions seem simple yet I can't find anything that seems to explain it in plain language to me.



Thank you



Answer



This particular "shelf" is an SAS (Serial Attached SCSI) drive array. SAS is like the SATA connection used in consumer computers for connecting hard drives, but more robust. Once of the things that it handles much better that SATA is multiple drives connecting over a single channel, or combining multiple channels to increase bandwidth.



What makes a SAN is the N: Network. Typical network technologies are Ethernet/IP or FibreChannel.



What you have is not a SAN. If it had a "controller" that connected via Ethernet/IP or FibreChannel, then it would be a SAN.



What you do have is DAS, or Direct Attached Storage. To connect it to your server, you will need an HBA (Host Based Adapter) that supports SAS. The drives will then appear to your OS as individual drives. Alternatively, you need an SAS RAID Controller. In the configuration of the RAID controller, you will define virtual drives made up of a group of disks in the drive array. Those virtual drives will be presented to your OS as a disk.


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