Mirrored Volume Resynchronization; Volume Resynchronization After Rebooting - NEC Express5800/320Ma Administrator's Manual

fault-tolerant volume. If one disk fails, the volume automatically uses the data from the
other disk.
Mirror all data volumes. Mirroring volumes as documented provides fault tolerance,
because volumes are mirrored on separate physical disks on separate FC buses.
When mirroring volumes, pair identical physical disks (same capacity, model, and
manufacturer) so that in the event of a disk failure, an entire physical disk can be
replaced without any data loss. See
System" on page 4-24

Mirrored Volume Resynchronization

When a volume is mirrored across two physical disks, and one of the disks fails or is
brought offline for any reason, the remaining good disk continues to operate. However,
the data on the mirrored volumes is no longer synchronized.
After a disk is replaced or brought back online, the mirror between it and the disk that
remained in operation must be resynchronized. During resynchronization, the system
copies the format and the contents of the good mirrored volume(s) to their mirror(s) on
the disk most recently brought back online.
Mirror resynchronization can occur automatically, or, in some cases, you must
resynchronize the mirror manually:
•
If you insert a replacement disk without a disk signature into the same slot as the
failed disk, the system automatically attempts to resynchronize the disk.
•
If you replace a failed disk with a blank basic or dynamic disk that contains a
signature, you must resynchronize the disks manually.
•
The system automatically attempts to resynchronize the disks if:
– An I/O element is removed and inserted.
– An I/O element goes offline and returns online.

Volume Resynchronization After Rebooting

After rebooting the system, and depending on the circumstances under which the
system was shut down, you may need to explicitly reactivate a failed mirrored partner
to resynchronize a volume.
for details.
N O T E
Because mirror resynchronization can severely affect
performance, you should resynchronize mirrors when the
system is least busy.
Using Volume Mirroring for Fault Tolerance
"Mirroring Disks in Your Express5800/320Ma
Disk Storage Management 4-21