If a disk encounters problems or fails, you perform a data slice regeneration to create a copy of the primary and mirror data slices on an available spare disk. During regeneration, the regular system processing continues for the bulk of the regeneration.
Note: In the IBM® PureData™ System for Analytics N1001 or IBM Netezza® 1000 and later models, the system does not change states during a regeneration; that is, the system remains online while the regeneration is in progress. There is no synchronization state change and no interruption to active jobs during this process. If the regeneration process fails or stops for any reason, the system transitions to the Discovering state to establish the topology of the system.
You can use the nzspupart regen command or the NzAdmin interface to regenerate a disk. If you do not specify any options, the system manager checks for any degraded partitions and if found, starts a regeneration to the appropriate spare disk automatically and in some circumstances when the disk regen is not kicked automatically, the manual regen is needed, which can be handled by support.
You can then use the nzspupart show -regenstatus or the nzds show -regenstatus command to display the progress and details of the regeneration. Sample command output follows for the nzds command, which shows the status for the data slices :
[nz@nzhost ~]$ nzds -regenstatus
Data Slice Status SPU Partition Size (GiB) % Used Supporting Disks
Start Time % Done
---------- --------- ---- --------- ---------- ------ ----------------
19 Repairing 1057 3 356 5.80 1040,1052
20 Repairing 1057 2 356 5.81 1040,1052
Note: Regeneration can take several hours to complete. If the system is idle and has no other activity except the regeneration, or if the user data partitions are not very full, the regeneration takes less time to complete. You can review the status of the regeneration by using the nzspupart show -regenStatus command. During the regeneration, user query performance can be impacted while the system is busy processing the regeneration. Likewise, user query activity can increase the time that is required for the regeneration.
A regeneration setup failure could occur if the system manager cannot remove the failed disk from the RAID array, or if it cannot add the spare disk to the RAID array. If a regeneration failure occurs, or if a spare disk is not available for the regeneration, the system continues processing jobs. The data slices that lost their mirror continue to operate in an un-mirrored or Degraded state; however, you should replace your spare disks as soon as possible and ensure that all data slices are mirrored. If an un-mirrored disk should fail, the system will be brought to a down state.
Overview - Disk Regeneration :
nzds – dataslice stats
-> -show : display information about dataslices (default)
-> -detail : includes Spu Location, Primary Storage Location, Mirror Storage Location & Size
-> -issues : shows any issues with dataslice regen
-> -regenStatus : show the status on disk regen
- No state transition when a disk fails over
- No interruption to service when the failover happens
- No interruption to service when the regenerated disk comes back into service
- Remembers where it left off after clean shutdown
- After a crash or power cycle will start over from the beginning
Data Slice States :
The data slice is operating normally and the data is protected in a redundant configuration; that is, the data is mirrored (for Netezza 100, Netezza 1000, or N1001 systems), or redundant (for Netezza C1000 systems).
The data slice is in the process of being regenerated to a spare disk because of a disk failure.
The data slice is not protected in a redundant configuration.
Another disk failure could result in loss of a data slice, and the degraded condition impacts system performance.
For Regen stuck issues, please contact support for immediate resolution.