12 February 2004
Yariv Glazer presents: iSCSI Overview Current State of the Technology Started with scsi and tried to emulate the fiberchannel network. Corparate Introduction YaGUSA Technology, a part of the YaGUSA Group, is a high level system intetrator and consultant specializing in enhanced services such as unified messaging, smart messaging, etc. iSCSI Protocol iSCSI sits on top of tcp/ip (not udp due to reliability issues) SCSI layer talks to both the SCSI device controller and iSCSI via the NIC Encapsulation: IP network +-> TCP/IP +-> iSCSI +-> SCSI Commands/Data - sessions between initiator and target - each session contains one or more connectiosn - each connection goes through a login phase + iSCSI help make offsite (or just off-host) backups practical - tcp can saturate 1 ghz of cpu per 1 gpbs line speed - networking speeds outpacing server and storeage speeds - tcp/ip acceleration no longer an option -- IT IS ESSENTIAL! iSCSI HGA - features to look for - complete offload - OS support: NT/2000/Win2003 & Linux - supports both network interfaces (RJ45 and LC) iSCSI host connectivity high availability, security and comparisons iSCSI over tcp/ip session maintained as connections migrate IP take over and take back using heartbeat packets Symmetrical and Asymmetrical Mirroring Data replication network based -- switch with volume management iSCSI "switches" handle the mirroring (they're much more than a switch; the name was chosen so as to not confuse Suits) Multi-platform mgt - host independent - simplify management Performance - does not consume host CPU - no bottleneck - load balancing between boxes - no latency addion over iscsi scalability - no limitation on the number of hosts - amount of storage is scaled by the number of switch elements high availability - no single point of failure Journaling - important for large systems. snapshots can be problematic if data is not flushed to disk (e.g., Oracle) -- very nice nonetheless, due to the speed This is neat stuff -- keep an eye open for it.