Active Network Systems Ltd

PathGuard for MPIO

PathGuard builds multiple I/O paths from host server to virtual disks in Arena RAID systems. The I/O can be dynamically distributed over the paths so as to utilize all possible bandwidth. The multiple physical paths are presented to operating system as a single high-performance logical path. PathGuard offers selective load balancing mode to meet different performance requirements. When an I/O path is down, like loose cable or failed HBA port, PathGuard will redirect I/O from the faulty path to the other healthy path; while the faulty path is recovered, PathGuard will automatically utilize the recovered path.

Enhances performance
Under PathGuard, a virtual disk can serve I/O concurrently via multiple paths, thus eliminates the limitation of the maximum data transfer rate of a logical disk which bounded by the maximum data transfer rate of single I/O path. In addition, the bandwidth of all paths would be fully utilized if the loading on different virtual disks is uneven. Because PathGuard transfers data over all workable paths, the utilization of path bandwidth as well as the ROI (Return-On-Investment) can be largely improved.

Improves system availability
PathGuard helps protect system against path failures. Pathguard would detect the path failure and redirect the I/O to healthy path, help to prevent for system down due to single path failure and to improve the business continuity. PathGuard keeps monitoring the status of all paths and notify users of any status change. All events concerning to paths are recorded to the system log for history tracking. The configuration and management are based on web-based GUI.

Simplifies management
With the dynamic load balancing offered by PathGuard, users would free from worrying about bandwidth planning or performance tuning. When there are new I/O added, the bandwidth created can add the new path to the PathGuard instantly. Together with the Symmetric Storage Presentation (SSP) feature offered by the Arena RAID systems firmware, users can easily mapping the logical disks to the host computer without caring about which paths to be used.

PathGuard outperforms host-based software striping (RAID 0)
Some host-based software RAID also utilizes multiple paths to serve I/O for single logical drive on a host system. However, there are some significant differences between the two approaches. First, PathGuard can deliver tolerance of path failures which S/W RAID would not have the same feature. Second, software RAID forces I/O to be truncated into data stripes, which results in unnecessary overhead and having limited size of data transfer in single I/O (for example, the data transfer size of single I/O in Windows software RAID is up to only 64KB). Furthermore, software RAID stores RAID configurations on the data area, which can be accessed by applications running on the server, and user data will be completely gone if the RAID configurations are corrupted.

Support Model

JanusRAID II: SA-4551S, SA-6651S, SA-6651E, SS-4551E, SS-4552E, SS-6651E, SS-6652E, SS-4501E, SS-4501R, SS-6601E/R, SS-6602E/R, SS-6603E/R, SS-8801E/R, SS-8802E/R

JanusRAID: SA-6641D, SA-6640S, SA-6641S, SA-4540S, SA-4541S, SA-4340S, SA-4341S