Mirroring Disks - NEC Express5800/320Ma Software Installation And Configuration Manual

Mirroring Disks

For optimal performance, use Rapid Disk Resync (RDR) disk mirroring, as described
in "Using RDR to Mirror Disks in Internal Storage" on page
managed disks in the internal storage enclosure. RDR disk mirroring is supported only
on internal disks. With RDR disk mirroring, you mirror pairs of physical disks to create
virtual disks. Each pair of mirrored disks constitutes one virtual disk. The data on one
disk is replicated in full on the corresponding disk. RDR disk mirroring does not create
volumes.
RDR offers faster resynchronization of mirrored disks than other mirroring methods
after transient failures or when a single disk is briefly removed from service.
If you configure RDR disk mirroring, you can leave disks as basic volumes, or you can
use a disk-management tool to create striped volumes, which provides RAID1+0.
Use a disk-management tool to create mirrored volumes on disks in external storage
enclosures. See the Express5800/320Ma: System Administrator's Guide for guidelines
to ensure data fault-tolerance of volumes on disks in external storage enclosures.
N O T E S
1. If you use a disk-management tool to mirror disks,
make sure neither disk is a plex of an RDR virtual
disk.
2. Do not partner RDR and non-RDR system disks in a
mirror. Otherwise, the disks will fully resynchronize
after every restart if the RDR disk is not the primary
boot volume from which the system is booted.
3. If you create an RDR virtual disk from two physical
disks, only one disk appears in the disk-management
tool.
N O T E S
1. On the system disk, the IPL procedure creates a boot
partition that contains the operating system and all of
its components. Because the system disk and boot
partition hold system-critical files, such as the paging
file and system event files, limit the traffic to this disk
to system traffic only.
2. You can greatly reduce application downtime when
you upgrade software by installing and using the
optional NEC Solutions (America), Inc.
Express5800/320Ma Active Upgrade™ Software. If

Mirroring Disks

3-8, to configure and create
Configuring Software 3-7