Formatting A Logical Unit - Acer HDS AMS200 Reference Manual

7.4.7

Formatting a Logical Unit

Note 1: For the logical unit that is being formatted in the background, it is best to perform
operations to the host installation.
If a volatile failure for data in cache memory occurs due to subsystem power-off during
formatting, the logical unit will be unformatted and data can be lost. Therefore, host
installation operation should be performed from the first step for the logical unit.
Note 2: When logical units are formatted, the user data will be initialized and completely
deleted.
Note 3: The RAID group is allocated to the NAS system LU when the NAS is connected; the
user LU cannot be deleted without releasing the allocation.
Note 4: Formatting will impact host access performance, especially on the logical unit being
formatted and on the logical unit in the same RAID group as the logical unit being formatted.
Perform formatting functions during off-hours with less host access.
When formatting the logical unit in the same RAID group as NAS system LU, do not boot or
reboot the NAS OS. This could result in boot failure or increase the boot time of NAS OS.
Format
This mode enables the subsystem to start its operation earlier by formatting the
specified LU in the background to make it usable by a host. Up to 512 LUs can be
specified for formatting. This number can also be increased; however, the number of
LUs that can be simultaneously formatted in the background is six per CTL. When
executing formatting, the Storage Navigator-Modular program can perform operations
(such as a RAID group creation) while the formatting is being executed.
When the Storage Navigator-Modular program is terminated while formatting is executed,
the formatting function is continued. When the Storage Navigator-Modular program is
terminated while formatting is executed, the formatting progress is displayed by
percentage in the logical unit status column when the Storage Navigator-Modular
program is activated again.
When the host I/O is executed for the LU in formatting, Format completion may be
delayed; from the 99 % progress status, it may take 400 seconds (maximum).
146 Chapter 7 Configuring Storage on the Thunder 9530™ V Series Subsystem