Migrating a Disk Group
PowerVault MD Storage Manger (MDSM) allows you to migrate a disk group by
exporting the disk group and then importing it to another storage array. You can
also export a disk group to store data offline.
When you export a disk group, all the physical disks become offline. To ensure
that the export is successful, at least two physical disks that are not part of the
disk group you are migrating must be present in the storage array.
When you migrate the exported disk group to the new storage array, the import
fails if a majority of the physical disks are not present in the group. For example,
both the physical disks in a two-disk RAID 1 configuration, or the three physical
disks (one from each disk pair) in a four-disk RAID 10 configuration must be
present.
RAID Controller Clock Synchronization Using NTP and SNTP
Your PowerVault MD series RAID controller firmware independently monitors
Network Time Protocol (NTP) or Simple Network Time Protocol (SNTP) server
messages and updates its time-of-day clock. After the RAID controller receives a
broadcasted NTP or SNTP server message and the controller clock is adjusted,
the controller firmware enforces an eight-hour delay. During the eight-hour time
frame, no subsequent NTP or SNTP messages are monitored. The eight-hour
delay prevents a rogue or malfunctioning NTP or SNTP server from causing
excessive clock management activity on the RAID controller, leading to
interference with normal controller processing.
NOTE: Configure the SNTP server to deliver broadcast messages to the 255.255.255.255
IP address.
Maximum Physical Disk Support Limitations
CAUTION: If you are using a RAID 0 or RAID 10 configuration, do not attempt to create
virtual disk groups exceeding the 120-physical disk limit.
Although the PowerVault MD storage arrays that come with premium feature
activation can support up to 192 physical disks, RAID 0 and RAID 10
configurations with more than 120 physical disks are not supported. MDSM does