| PRIMEQUEST System Disk Mirror for Windows User's Guide V1.0 |
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Contents
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| Chapter 1 Functions |
PRIMEQUEST System Disk Mirror for Windows (PSDM) is software which improves the availability of the PRIMEQUEST system by mirroring the system disk where Windows is installed.
The mirroring function replicates the data of one disk onto other separate disks in real time. This way if any one of the disks fails, the system can continuously access the data on the disks functioning normally, and thus maintain system availability.
If the master disk unexpectedly becomes unrecognizable for the OS during system operation, the service or system may stop operating. This is because information on the unrecognizable disk partition (such as C: or D:) is deleted automatically by the OS and the partition will be no longer accessible from the OS or applications. Even in this event, data is maintained on the disk in normal status, and operation can simply be resumed through system reboot. A disk may become unrecognizable for the OS, for example, if a disk path failure or power failure occurs or if the disk is removed accidentally. Unrecognizable disks are not indicated with the sdxinfo -P command.
PSDM has the following features.
This software mirrors the entire system disk including the EFI System Partition (ESP) and the Microsoft Reserved Partition (MSR).
In the event that the system disk fails, the user can boot from one of the mirror disks. The EFI boot entry required for the booting is automatically created for each mirror disk when mirroring setup is completed. If the mirroring configuration or state is changed, the EFI boot entry will also be updated automatically.
If a system failure occurs, the I/O process may be interrupted. Therefore, the data equivalence between the mirrored disks will no longer be guaranteed. To resynchronize the disks, data copying is automatically performed after the system is rebooted.
The Just Resynchronization Mechanism (JRM) is a mechanism that speeds up this resynchronization. JRM realizes high-speed resynchronization by initiating the copy from the region that may be out-of-sync due to the failure instead of replicating the entire disk data.
Just resynchronization copying on the boot disk
JRM does not function on the boot partition (usually C:). On this partition, full resynchronization copying will be performed after the reboot following the system failure. For example, if ESP, C: (boot partition), and D: exist on the boot disk, only out-of-sync regions are copied for ESP and D: but the entire partition is copied for C: in that event.
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