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SuperSyncTM Disk Array for Stratus VOS Continuum SCSI Model Protect your data in the event of a drive failure even while running simplexed during a rebuild!
SuperSync Disk Array The SuperSync Disk Array was designed to emulate a tray of VOS disks with no user intervention or configuration required. Once the SuperSync Disk Array is connected to the Stratus host and powered up, the disks are set up, initialized, and mounted with the exact commands as standard VOS disks. Data Protection Even with duplexing, when using standard magnetic drives, data will be lost if a second failure occurs before the replacement drive is restored to service. When disks were small and rebuild times were short susceptibility to a second disk failure may have been acceptable. However, as disk drives have grown larger and larger, the window of exposure to a catastrophic data loss has greatly increased. During a rebuild, if the surviving drive fails gigabytes of critical data will be lost. A 34 or 36 Gigabyte disk could take a day or longer to resynchronize after the new disk is powered on. This is not so with SuperSync. SuperSync Disk Arrays provide parity protection even when running simplexed during a rebuild. SuperSync will continue processing data even if a disk is lost. Therefore, no data will be lost. Physical Connections The SuperSync connects directly into a Stratus VOS Continuum via the K450/K460 BIO port as shown here. The Stratus host sees the SuperSync as one or more standard VOS disks.
SuperSync is available in a 2U (3.5 in.)/408 GB version. This allows approximately 408 GB of duplexed redundant storage in 7 inches of rack space. The VOS addressable capacity is equal to 12 Stratus D712 disks. Configuration Options The SuperSync is shipped from DRA in a fully configured, pre-tested, un-initialized, and ready-to-run condition. Normally there is no need to change any internal settings on the SuperSync. SuperSync stores data on one or more virtual VOS disk types. The virtual disk types match so exactly the equivalent physical disk type that a virtual disk can be duplexed with an equivalent physical disk.
SuperSync Disk Arrays provide internal redundancy. The SuperSync is configured with a parity drive. If one drive fails, the others keep running. No data or processing time is lost. The SuperSync can be duplexed just like standard magnetic disk drives, providing external redundancy. SuperSync uses virtual device ids. Storage can be partitioned at the SCSI device id and Logical Unit Number (LUN) level so a single channel can address multiple virtual partitions as if they were distinct physical devices. A single SCSI cable can thus support up to 15 devices (VOS is limited to 12 ids) and a partition can be defined as any size the system may require (VOS SCSI partitions are limited to 34 GB). Internal Operation When a VOS application issues an I/O request, the VOS I/O subsystem converts it to a physical I/O command. The BIO (K450/K460) then passes this command to SuperSync over the Stratus SCSI bus. SuperSync responds to each VOS physical I/O command exactly as a standard VOS disk would respond. In order to accomplish this disk emulation, SuperSync converts the Stratus disk address into an address for the corresponding data on the target, performs the appropriate I/O operations on the target, then converts data and status returned by the target into an appropriate response for the BIO (K450/K460). Product Support Internally available OS features allow DRA to support SuperSync via remote dial-in connections. Parts are easily replaced and drive bays are hot pluggable. Internal power supplies are redundant. DRA products purchased directly from DRA are supported through the Co-active Maintenance Service (CMS). CMS is a total support agreement which is available "around the clock, around the world" to participating DRA customers. Product maintenance, product updates, documentation and training are available through CMS support. CMS is provided free of charge for 90 days following product installation, and may be extended by contract thereafter.
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