HP NetRAID 1 Controller - Manual (Page 9)

5
SCSI Firmware
The HP NetRAID Series firmware handles all RAID and SCSI command processing and also
supports the functions described in the following table.
Feature Description
Disconnect/Reconnect Optimizes SCSI Bus seek
Tagged Command Queuing Multiple tags to improve random access
Scatter/Gather Multiple address/count pairs
Multi-threading Up to 255 simultaneous commands with elevator sorting and
concatenation of requests per SCSI channel
Stripe Size Variable for all logical drives from 4 KB to 128 KB. Note: 128 KB
stripe is not supported with 4 MB of memory or less.
Rebuild Multiple rebuilds and consistency checks with user definable priority
Functions Supported by HP NetRAID Series Firmware
Automatic Failed Drive Detection and Rebuild
The adapters firmware automatically detects and rebuilds failed drives, which can be done
transparently with hot spares.
Drive Roaming
The adapters have the ability to determine when disk drives have been physically moved from one
slot to another, as in a hot swap (on the same adapter).
Hot Swap Manual Replacement
The adapters support the manual replacement of a hot swap disk unit in the RAID subsystem without
shutting down the system.
Battery-backed Cache Memory (HP NetRAID Only)
A battery module (on a mezzanine card) is supplied to provide backup power for the cache in case of
a power failure. This backup power prevents cache data loss.
The HP NetRAID Battery backup module protects the data handled by the HP NetRAID Adapter by
providing protection from power supply interruptions to the HP NetRAID cache memory. The HP
NetRAID Battery backup module monitors the voltage level of the DRAM modules installed on the
HP NetRAID card and supporting circuitry. If the voltage drops below a predefined level, the
Battery backup module switches the memory power source from the HP NetRAID card to the battery
pack attached to the HP NetRAID Battery backup module. As long as the voltage level is below the
predefined value, the HP NetRAID Battery backup module provides the memory refresh cycles
necessary to retain the contents of the HP NetRAID memory modules. If the voltage level returns to
an acceptable level, the HP NetRAID Module switches the power sources back to the HP NetRAID
adapter card. The battery supports 48-hours or greater retention for a standard 4 MB cache memory.
NOTE When using SNMP monitoring with the NetRAID-1 adapter, you may see
messages that the battery module is missing. Disregard these message, as the
NetRAID-1 adapter does not include a battery module.