Promise - Jigsaw Systems Ltd

Apple Promise VTrak RAIDs are designed to keep running thanks to easy remote management through the web interface
Active/active RAID controllers for failover/failback capability
Up to two controllers per E-Class subsystem to ensure high performance and availability
Two 4Gb fibre channel ports per controller and 2GB cache per controller
You can even mix SATA and SAS drives in the same enclosure, for best combination of high performance and low storage cost
Upgrade from Single to Dual Controller at a later date, simply purchase the optional E-Class service parts kit (X220ATA)
Add up to 4 x J-Class 16 bay expansion units per E-Class RAID, giving a total of 80 drive bays for up to 80TB storage

Each controller features 2 built-in 4Gb Fibre Channel ports for high-speed access to your data
Great scalability! 4TB single controller system is fully upgradeable up to dual controllers, 80TB!
Single controller is obviously less expensive

Lightning performance - up to 1,400MB/s!
Complete redundancy - controllers operate active/active. If one fails traffic automatically routes across the second controller

SATA - maximum capacity, minimum price
SATA is ideal for streaming data, storage, backup
SAS - highest performance of any mechanical storage, up to 4 times the performance of SATA!
SAS is ideal for databases, web servers, application servers, or anything requiring non-sequential data access
Mix SATA and SAS to cut down on space requirements, power drain, maintenance, support costs

Apple Promise VTrak RAID supports all major RAID levels, including RAID 5 and RAID 6
RAID 5 uses 1 disk for parity
- - If you lose a disk in your array, data is safe
- - The RAID rebuilds from parity data
- - Data is at risk of another failure - as rebuilding takes upwards of 24 hours
RAID 6 uses two disks for parity
- - Can withstand 2 failures before data is at risk
RAID 5 for faster data access
RAID 6 for safer, more suited for large arrays

Promise RAID for Xserve