Write Caching; Read-Load Balancing - NEC Express5800/320Ma Administrator's Manual

Using RDR for Fault Tolerance
or is removed from service during resynchronization, the source disk continues
operating in simplex mode.
If the system starts to shut down while an RDR virtual disk is resynchronizing, RDR
records the state of the resynchronization and, upon system reboot, resumes
resynchronization from that point.

Write Caching

To optimize system performance, you can enable write caching on RDR virtual disks.
By default, write caching is disabled, except during disk resynchronization, when it is
automatically enabled.
Write caching does not work on a simplex RDR virtual disk (except when it is
resynchronizing), even if it is enabled. However, if you enable write caching on a
simplex disk that is later duplexed, write caching will work.
To enable write caching
1. Right-click My Computer on the desktop, select Manage, select Device Manager,
and then expand Disk Drives.
2. Select the target disk, select Properties, and click the Policies tab.
3. Check Enable write caching on the disk, and click OK.

Read-load Balancing

When you enable read-load balancing, read operations on duplex RDR virtual disks
alternate between the two physical disks, which improves performance. By default,
read-load balancing is enabled on all RDR physical disks.
You can enable or disable read-load balancing either
for all RDR physical disks across the system.
To enable or disable read-load balancing for a single physical disk
1. In ftSMC, expand ftServer I/O Enclosures and Logical Disk Information.
2. Right-click the target RDR Virtual Disk.
3. Select Set Rdr Lun Load Balancing.
4. In the dialog box, set the Rdr Lun Load Balancing field to On or Off, and click
Finish.
4-6 Express5800/320Ma: System Administrator's Guide
N O T E
Global read-load balancing settings do not overwrite
read-load balancing settings on individual RDR physical
disks.
for each physical disk or globally,