6760 ServerNet/DA Manual

Introduction to the 6760 ServerNet/DA
6760 ServerNet/DA Manual—424879-003
1-5
Limitations
associated with the primary drive can occupy a separate enclosure from the
primary path and backup path associated with the mirror drive.
This arrangement, called “enclosure interleaving,” offers increased fault tolerance.
For more information, see Disk Configuration for Fault Tolerance on page 1-10,
and the NonStop S-Series Planning and Configuration Guide.
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ServerNet Fabric. The 6760 adapter can communicate with only one ServerNet
fabric in any slot it is installed in. For increased fault tolerance, disk modules must
be connected to separate 6760 adapters that are installed in an odd-numbered slot
and an even-numbered slot.
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SAC Types. You cannot mix different SAC types or different device types on the
same 6760 adapter.
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System Disk. $SYSTEM disks cannot be controlled by a 6760 adapter.
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Tape Load. The system cannot be loaded from a tape drive that is connected to a
6760 adapter. If you plan to perform tape loads, you must have at least one tape
drive connected to the SCSI port of an I/O multifunction (IOMF) CRU or processor
multifunction (PMF) CRU.
•
519x Tape Drives. Some 519x tape drives with older revision levels will not function
properly if attached to a NonStop S-series system. If you are planning to move a
519x tape drive from a NonStop K-series system to a NonStop S-series system,
contact your service provider to determine the minimum engineering revision level
required.
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Daisy Chaining. Daisy-chaining tape drives (connecting two tape drives serially on
the same SAC) is supported but not recommended. Problems can occur when two
tape drives are attached to the same SAC. If one tape drive gets errors that cause
the system to issue a SCSI bus reset, both drives are reset. When the system tries
to access either drive, it might report errors such as file-system error 190 (device
interface error), 218 (device command timeout error), or 224 (DMA error). These
problems can be avoided by configuring a separate SAC for each tape drive.
Open SCSI devices can be daisy-chained on an S-SAC.
Caution. When you replace a PMF CRU or IOMF CRU, the ServerNet fabric connection
supplied by that CRU is no longer available. If devices are supported by only one 6760 adapter,
those devices must be stopped when the related PMF CRU or IOMF CRU is replaced. See
Preparing to Replace a PMF CRU or IOMF CRU
on page 4-17.