HP NetRAID 1Si Controller - Manual (Page 115)

Chapter 6 Capacity Expansion
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Precautions
When using the Online Capacity Expansion feature, it is very important that you
do not create volumes that exceed the actual physical capacity. You must add up
the capacities of all volumes that may be using the physical storage space, such as
a DOS volume, SYS volume, Hot Fix Area, and any user volumes. This is most
important if NetWare 4.2 will be installed on the disk array (rather than a SCSI
disk outside of the HP NetRAID system). During installation, if the total physical
capacity is exceeded during volume creation, a NetWare abend and loss of the
installation occurs. As long as the physical capacity is not exceeded, the
installation will be successful.
Although undesirable, NetWare 4.2 allows you to create volumes into the virtual
space. (This is because during volume creation, NetWare 4.2 only looks at the
beginning of the volume, and if there is real storage space there, the volume will
be created.) However, when writing to this volume, you cannot write beyond the
physical limit; write errors will be generated when the physical space is filled.
You need to be careful when creating volumes in a partition containing virtual
space. Use the HP NetRAID Config module to check the actual physical capacity
available, and be sure the total size of NetWare volumes does not exceed this
value.
One other useful measure is to set the capacity alarms under NetWare 4.2 so that
warnings will be generated when you approach the limit of a volume.
The Online Capacity Expansion feature cannot be used if a logical drive spans
multiple arrays. Each array can contain only one logical drive. Reconstruction (for
the purposes of adding a drive to an array) can be done only on an array having a
single logical drive. It is also important to plan future storage expansion into your
installation. This ensures that you can easily expand capacity without the need for
backup/restore operations or reconfiguration.
NOTE SFT-3 and mirroring users: Novell’s NetWare 4.2 operating
system, which provides system level fault tolerance by
mirroring two systems, is not compatible with the Online
Capacity Expansion feature. SFT-3 mirrors disk storage on a
partition basis rather than a volume basis. Because of the
virtual space created within the partition, SFT-3 cannot
successfully mirror the partitions. This limitation also applies
to regular mirroring (without SFT-3) of volumes. SFT-3 users
may add storage capacity online without bringing the two
systems down if enough drives are added to create a new array
and logical drive on an HP NetRAID Series adapter or on an
integrated HP NetRAID controller. Under the Install module,
NetWare 4.2 can then scan for new devices and detect the new
logical drive.