36 OES 2: NetWare Traditional File System Administration Guide
novdocx (en) 6 April 2007
NetWare partitions consist of up to 8 volume segments. Each segment can be allocated separately as
a member of a different Traditional volume. If you mirror a partition, the volume segments it
contains are mirrored on the mirror partition. For a Traditional volume that spans multiple server
disks, only its volume segments in that particular partition are mirrored. The volume segments on
other partitions on the same or different server disks remain unprotected. To fully protect your
Traditional volume, you must create a RAID1 device for each Traditional NetWare partition that
contains one of the volume’s segments.
5.1.2 Key Concepts for Mirroring Traditional NetWare Partitions
The following are important concepts for mirroring Traditional NetWare partitions:
All member partitions of a software RAID1 device must be of the same type. A Traditional
NetWare partition can only be mirrored to other Traditional partitions.
Each member partition in the software RAID1 device must be compatible in data area size.
The new partition must be at least the same size or slightly larger than the other partitions in the
group. The physical size of the partition must be at least 100 kilobytes (KB), but no more than
120 megabytes (MB) larger than the data size of the existing partitions in the mirror group.
All member partitions in the software RAID1 device must have the same sharable status. Either
all are sharable for clustering, or all are not.
Partitions you add to the software RAID1 device cannot be members of any other software
RAID device. They must be standalone partitions.
Only partitions marked with the Mirror attribute can be used as a software RAID1 mirrored
partition. You must set the Mirror attribute for partitions when you create them; you cannot add
the option later.
Although you can mirror one partition to as many as four other partitions, mirroring two
partitions is typically sufficient fault tolerance for most systems.
If a mirrored disk fails and cannot be accessed by the server, you can unmirror the server’s
partitions on the functional disk, then salvage the lost volume segments.
If you want to remove a hot-plug mirrored disk without bringing down the server, you must
unmirror the disk first.
5.1.3 Improving Fault Tolerance for Software RAID1 Devices
with Duplexing
Mirroring stores the same data on separate disks on the same controller channel. If you mirror
partitions on separate disks over different controller channels or host bus adapters, this is called
duplexing. Duplexing can also concurrently use two instances of a driver for the channels.
Duplexing is the recommended method for fault tolerance because two channels rarely fail
simultaneously.
The process for mirroring and duplexing is the same. The term mirroring is used in all menus in
Novell Remote Manager for NetWare to refer to both mirroring and duplexing.
