HP LH4r Installation and configuration of the HP NetRAID, NetRAID-1 and NetRAI - Page 14

SCSI Termination and Firmware

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Chapter 1 Introduction • For the HP NetRAID-1 adapter, cache memory resides in a 4 MB nonbattery-backed 60-ns FPM DRAM SIMM and cannot be upgraded. NOTE The HP NetRAID-1 adapter does not have a Battery Backup Unit. The HP NetRAID Series adapters support Direct and Cached I/O and Write Through or Write Back caching, which can be selected for each logical drive. To improve performance in sequential disk accesses, the HP NetRAID Series adapters use Adaptive Read Ahead caching by default, but it can be disabled to Normal or set to simple Read Ahead caching. Alarm: The HP NetRAID Series adapter's onboard tone generator provides audible warnings (alarms) when RAID system errors occur. SCSI Termination and Firmware Termination: Active termination on the SCSI bus conforms to Alternative 2 of the SCSI-2 specifications. Termination enable/disable is automatic through cable detection. It can be modified by the user in Step M in Chapter 6. Firmware: The HP NetRAID Series firmware handles all RAID and SCSI command processing and also supports the following functions: • Disconnect/Reconnect feature optimizes SCSI Bus seek. • Tagged Command Queuing allows multiple commands to be sent to the controller, thus improving random access. • Scatter/Gather supports multiple address/count pairs. • Multi-threading supports up to 255 simultaneous commands with elevator sorting and concatenation of requests per SCSI channel. • Stripe size for each logical drive can be set from 4 KB to 128 KB. A stripe size of 128 KB requires at least 8 MB of memory. • Multiple rebuilds and consistency checks have user-definable priority. 6

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Chapter 1
Introduction
6
•
For the
HP NetRAID-1
adapter, cache memory resides in a 4 MB non-
battery-backed 60-ns FPM DRAM SIMM and cannot be upgraded.
NOTE
The HP NetRAID-1 adapter does not have a Battery Backup
Unit.
The HP NetRAID Series adapters support Direct and Cached I/O and Write
Through or Write Back caching, which can be selected for each logical drive. To
improve performance in sequential disk accesses, the HP NetRAID Series
adapters use Adaptive Read Ahead caching by default, but it can be disabled to
Normal or set to simple Read Ahead caching.
Alarm:
The HP NetRAID Series adapter’s onboard tone generator provides
audible warnings (alarms) when RAID system errors occur.
SCSI Termination and Firmware
Termination:
Active termination on the SCSI bus conforms to Alternative 2 of
the SCSI-2 specifications. Termination enable/disable is automatic through cable
detection. It can be modified by the user in Step M in Chapter 6.
Firmware:
The HP NetRAID Series firmware handles all RAID and SCSI
command processing and also supports the following functions:
•
Disconnect/Reconnect feature optimizes SCSI Bus seek.
•
Tagged Command Queuing allows multiple commands to be sent to the
controller, thus improving random access.
•
Scatter/Gather supports
multiple address/count pairs.
•
Multi-threading supports up to 255 simultaneous commands with elevator
sorting and concatenation of requests per SCSI channel.
•
Stripe size for each logical drive can be set from 4 KB to 128 KB. A stripe
size of 128 KB requires at least 8 MB of memory.
•
Multiple rebuilds and consistency checks have user-definable priority.