This article will explain about the rare instance where replacing RE with NGRE on MX-960 lead to failure of NGRE due to hard disk related errors.

In certain instances replacing SCB and RE modules from Enhanced MX CB to SCB2 modules with NGREs lead to RE hard disk failures, where it will get stuck in present state. 

Routing-Engine will get hanged and stuck in present state. We will see below console logs on RE. The vhclient tries to invoke "parted" on the Secondary Disk (sdb) during issue with Secondary Disk. Below Warning Message along with series of messages are observed then :-

ata6.00: status: { DRDY ERR }

ata6.00: error: { ABRT }

ata6.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x0

ata6.00: irq_stat 0x40000001

ata6.00: failed command: FLUSH CACHE EXT

ata6.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 26

res 51/04:00:00:00:00/00:00:00:00:00/a0 Emask 0x1 (device error)

ata6.00: status: { DRDY ERR }

ata6.00: error: { ABRT }

end_request: I/O error, dev sdb, sector 0

Warning: Error fsyncing/closing /dev/sdb: Input/output error

When the issue happens , the SSD Card DRDY Error might be seen and system might end up in GRUB Mode.

Direct Memory Access (DMA) is used to Access the System Memory during the Boot Process and any Failure in reading the DMA could be due to Possible Disk Corruption.

This could be a Hardware Issue with Disk Or Issue with Corrupt Partitions.

> Try with reseating RE

> If issue persists then perform USB Installation for Junos OS on Primary And Secondary Disk.

• Insert the USB disk in the USB slot on the Routing Engine.
• After the Routing Engine boots from the USB, press y when you are prompted to confirm Install vmhost and Junos software on Primary and Secondary disk [y/N? on the console.
• After the installation is completed, press y when prompted to confirm Reboot now? [y/N]? to reboot from the SSD disk.

> If issue persists then, please contact JTAC Support immediately, as we might need a replacement of RE

2024-06-12 :Initial Version