Supported Platforms
Related Documentation
- ACX Series
- Understanding How the Primary Junos OS Image with Dual-Root Partitioning Recovers on the ACX Series Router
- Installing Junos OS Using a USB Storage Device on ACX Series Routers
- Installing Junos OS Upgrades from a Remote Server on ACX Series Routers
- Example: Installing Junos OS and Configuring a Dual-Root Partition on ACX Series Routers Using the CLI
Dual-Root Partitioning ACX Series Universal Access Routers Overview
Dual-root partitioning allows the ACX Series router to remain functional even if there is file system corruption and to facilitate easy recovery of the file system. Dual-root partitioning means that the primary and backup Junos OS images are kept in two independently bootable root partitions. If the primary root partition becomes corrupted, the system can still boot from the backup Junos OS image located in the other root partition and remain fully functional.
 | Note: All ACX Series routers run with dual-root partitioning. |
This section contains the following topics:
Boot Media and Boot Partition on the ACX Series Routers
With dual-root partitioning, the ACX Series router first tries to boot the Junos OS from the primary root partition and then from the backup root partition on the internal NAND flash. If both primary and backup root partitions of the internal NAND flash fail to boot, you must insert a USB storage media with a copy of the Junos OS from which to boot.
The following is the storage media available on the ACX Series router:
- USB media emergency boot device
Note: The USB media device is not dual-root partitioned.
- Dual, internal NAND flash device (first daOs1, then daOs2)
Important Features of the Dual-Root Partitioning Scheme
The dual-root partitioning scheme has the following important features:
- The primary and backup copies of Junos OS images reside in separate partitions. The partition containing the backup copy is mounted only when required. With the single-root partitioning scheme, there is one root partition that contains both the primary and the backup Junos OS images.
- The request system software add command for a Junos OS package erases the contents of the other root partition. The contents of the other root partition will not be valid unless software installation is completed successfully.
- Add-on packages, such as jais or jfirmware, can be reinstalled as required after a new Junos OS image is installed.
- The request system software rollback command does not delete the current Junos OS image. It is possible to switch back to the image by issuing the rollback command again.
Related Documentation
- ACX Series
- Understanding How the Primary Junos OS Image with Dual-Root Partitioning Recovers on the ACX Series Router
- Installing Junos OS Using a USB Storage Device on ACX Series Routers
- Installing Junos OS Upgrades from a Remote Server on ACX Series Routers
- Example: Installing Junos OS and Configuring a Dual-Root Partition on ACX Series Routers Using the CLI
Published: 2013-01-11
Supported Platforms
Related Documentation
- ACX Series
- Understanding How the Primary Junos OS Image with Dual-Root Partitioning Recovers on the ACX Series Router
- Installing Junos OS Using a USB Storage Device on ACX Series Routers
- Installing Junos OS Upgrades from a Remote Server on ACX Series Routers
- Example: Installing Junos OS and Configuring a Dual-Root Partition on ACX Series Routers Using the CLI
