Another choice for building storage networks
By kgibson on Apr 04, 2005
Solaris 10 Update 1 will have an integrated iSCSI driver that sends SCSI commands and data over standard ethernet NICs. To applications, file systems, and volume managers, the iSCSI driver looks like the existing SCSI drivers so these layers will run the same on iSCSI/Ethernet as on parallel SCSI or Fibre Channel.
The disadvantage of the iSCSI driver is that more protocol execution is done by the processor, and more significantly, data is copied between user memory and ethernet buffers. Fibre, on the other hand, can DMA directly in and out of application memory as well as offload protocol processing to the HBA.
iSCSI offers at least two benefits though. One is lower cost. It runs on low cost NICs and ethernet switches. Second, the storage network can be managed, in part, using familiar ethernet protocols and tools.
We have customers who are planning to use Sun's rack-mount x64 servers in their data center and who plan to use iSCSI in the Solaris OS on these servers. They have evaluated the performance of these x64 servers and decided they have enough processing power to spare. They like that Solaris iSCSI is integrated (no adding extra patches) and have found it to perform very reliably when faced with a variety of hardware failures and storage network error scenarios. Most plan to bridge iSCSI to FC to access their existing consolidated SAN storage, and some are looking to use native iSCSI arrays.
So, data center administrators have another choice for building storage networks. Either way, the drivers are built-into the Solaris OS, they are highly available, extensively tested and, as always, open based on standards.