Juniper QFabric QFX3000-G Hardware Documentation page 899

CHAPTER 57
Restoring QFX3100 Volumes
Troubleshooting HDD Module Failures in a RAID Volume
Copyright © 2018, Juniper Networks, Inc.
Troubleshooting HDD Module Failures in a RAID Volume on page 849
Troubleshooting QFX3100 Director Device Isolation on page 859
The two QFX3100 hard disk drive (HDD) modules are organized as a RAID 1, or mirrored
configuration. If one HDD module fails or needs to be replaced, the remaining HDD module
becomes the primary drive in the RAID. The QFX3100 continues to operate with only the
primary drive, but the RAID does not operate optimally because there is no redundancy.
Normally, the primary drive is only used in standalone mode until you replace the failed
drive. You can replace the failed drive while the unit is running (hot-swap) and the RAID
automatically resynchronizes the primary drive to the new drive.
The system operation is severely degraded while the drive automatically synchronizes
the remaining drive to the replacement drive. Expect this synchronization process to take
at least 17 hours. If you remove the primary drive before the newer drive becomes
synchronized with the primary drive, you must re-create the RAID and reinstall the
QFX3100 software image.
CAUTION: If the primary (remaining) HDD module fails or is removed while
the RAID is synchronizing, the RAID contents are lost and cannot be recovered.
The independent failure of two drives is extremely rare. When one or both HDD modules
appear to fail, likely causes are:
One HDD module is not able to autocorrect, causing a hard failure. A replacement HDD
module can be hot-swapped with the failed module.
Both HDD modules have been removed from the QFX3100 and moved to another
QFX3100. The RAID becomes inactive and is not recognized as storage in the new
location. If the RAID is inactive, you can restore it using an internal controller utility to
activate the disk.
One HDD module has been removed and the new module inserted. However, before
the two drives are synchronized, the primary drive is removed. In this scenario, the
system loses track of the synchronization and corrupts the RAID. Once it has been
849