Customer was in a MW to recover RE-S-2X00x6 routing engine as they are having active alarm "VMHost 1 Boot from alternate disk" . They attempted to recover Routing Engine by performing an RE reboot and executing the "request vmhost snapshot recovery partition" command. Unfortunately, these methods did not resolve the issue.
Active Alarm
re0.labrouter> show chassis alarms
1 alarms currently active
Alarm time Class Description
2025-02-01 00:17:00 CST Minor VMHost 1 Boot from alternate disk
Routing Engine Console Logs
Finding primary SSD node for install
Device details
==============
device: /dev/sda
vendor: ATA
model: SFSA050GV3AA2TO-
size: 50020540416 bytes
Booting SSD2: EFI Hard Drive (SFSA050GV3AA2TO-I-LB-24A-JUN)...
Routing Engine BIOS Menu - Not Detected SSD1
Kernel (dmesg) logs reporting ATA1 failure
root@re1:~# demesg | grep ata
[ 0.000000] Command line: BOOT_IMAGE=/vmlinuz root=LABEL=jrootb_S ro quiet pcie_port_pm=off libata.force=noncq isolcpus=2-5 enforcing=0 pci=resource_alignment=00:1f.3;09:0d.0 rootdelay=5 unknown_nmi_panic=1 ro max_loop=255 console=ttyS0,9600 crashkernel=512M maxcpus=6 acpi_enforce_resources=lax
[ 0.000000] BIOS-e820: [mem 0x000000007b69f000-0x000000007b7fefff] ACPI data
[ 0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz root=LABEL=jrootb_S ro quiet pcie_port_pm=off libata.force=noncq isolcpus=2-5 enforcing=0 pci=resource_alignment=00:1f.3;09:0d.0 rootdelay=5 unknown_nmi_panic=1 ro max_loop=255 console=ttyS0,9600 crashkernel=512M maxcpus=6 acpi_enforce_resources=lax
[ 0.000000] Memory: 64780436K/66707860K available (11247K kernel code, 1306K rwdata, 4344K rodata, 1472K init, 840K bss, 1927424K reserved, 0K cma-reserved)
[ 0.945364] libata version 3.00 loaded.
[ 2.316795] ata1: SATA max UDMA/133 abar m2048@0x91d20000 port 0x91d20100 irq 35 <<< SDA
[ 2.316796] ata2: DUMMY
[ 2.316797] ata3: DUMMY
[ 2.316797] ata4: DUMMY
[ 2.316798] ata5: DUMMY
[ 2.316800] ata6: SATA max UDMA/133 abar m2048@0x91d20000 port 0x91d20380 irq 35 <<< SDB
...
[ 48.138079] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[ 48.211601] ata1.00: failed command: WRITE DMA
[ 48.252020] ata1.00: cmd ca/00:08:00:38:fb/00:00:00:00:00/e0 tag 14 dma 4096 out
[ 48.406580] ata1.00: status: { DRDY }
[ 48.436915] ata1: hard resetting link
[ 48.747834] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
[ 49.083661] ata1.00: configured for UDMA/133
[ 49.083664] ata1.00: device reported invalid CHS sector 0
[ 49.083668] ata1: EH complete
[ 79.879987] ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen
[ 79.953634] ata1.00: failed command: WRITE DMA
[ 79.994174] ata1.00: cmd ca/00:08:00:38:fb/00:00:00:00:00/e0 tag 15 dma 4096 out
[ 80.148726] ata1.00: status: { DRDY }
[ 1158.020280] ata1.00: status: { DRDY }
[ 1158.020283] ata1: hard resetting link
[ 1158.326701] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 310)
[ 1158.684456] ata1.00: configured for UDMA/33
[ 1158.684459] ata1.00: device reported invalid CHS sector 0
[ 1158.684469] sd 0:0:0:0: [sda] tag#0 UNKNOWN(0x2003) Result: hostbyte=0x00 driverbyte=0x08
[ 1158.684472] sd 0:0:0:0: [sda] tag#0 Sense Key : 0x5 [current]
[ 1158.684474] sd 0:0:0:0: [sda] tag#0 ASC=0x21 ASCQ=0x4
[ 1158.684476] sd 0:0:0:0: [sda] tag#0 CDB: opcode=0x2a 2a 00 00 0f f0 00 00 00 08 00
[ 1158.684478] blk_update_request: I/O error, dev sda, sector 1044480
[ 1158.684480] Buffer I/O error on dev sda3, logical block 0, lost async page write
[ 1158.684493] ata1: EH complete
…
Based on the logs, the primary disk (DISK0 or SDA or SSD1) is experiencing a hardware failure and is thus not detected by BIOS. This was the reason for the failure of the RE0 primary disk recovery. Since it was a disk hardware failure, Routing Engine replaced to resolve the issue