In this article, we explain a scenario where a QFX5120‑48Y may fail to boot properly when using fans other than those recommended in the official data sheet. We also outline how to recognize this issue before considering replacement of the device through an RMA.

• Instead of entering a boot loop (as typically seen when there is a hardware-related memory issue), the boot process stops entirely.
• The device is not recovering through either the recovery or format installation procedures.

There may be scenarios where a new or replacement QFX5120‑48Y fails to boot properly, becoming stuck during the boot process:

19:15:57 /packages/sets/active/boot/os-kernel/kernel text=0x5597c4 data=0x140 data=0x513b80 0x8+0xaca70+0x8+0x96110-

19:15:57 Verified /packages/sets/active/boot/os-kernel/kernel

19:16:00 /packages/sets/active/boot/os-kernel/contents.izo size=0x9f9600

19:16:00 Verified /packages/sets/active/boot/os-kernel/contents.izo

19:16:02 /packages/sets/active/boot/os-kernel/miibus.ko size 0x3c8a8 at 0x1851000

19:16:02 Verified /packages/sets/active/boot/os-kernel/miibus.ko

19:16:02 loading required module 'netstack'

19:16:10 /packages/sets/active/boot/netstack/netstack.ko size 0x172b750 at 0x188e000

19:16:10 Verified /packages/sets/active/boot/netstack/netstack.ko

19:16:11 /packages/sets/active/boot/os-kernel/iflib.ko size 0x21d98 at 0x2fba000

19:16:11 Verified /packages/sets/active/boot/os-kernel/iflib.ko

19:16:11 /packages/sets/active/boot/os-kernel/coretemp.ko size 0x2e38 at 0x2fdc000

19:16:11 Verified /packages/sets/active/boot/os-kernel/coretemp.ko

19:16:12 /packages/sets/active/boot/os-kernel/ichwd.ko size 0x7240 at 0x2fdf000

19:16:12 Verified /packages/sets/active/boot/os-kernel/ichwd.ko

19:16:12 /packages/sets/active/boot/os-kernel/if_em.ko size 0x6f100 at 0x2fe7000

19:16:12 Verified /packages/sets/active/boot/os-kernel/if_em.ko

19:16:13 /packages/sets/active/boot/os-kernel/if_fxp.ko size 0x10a30 at 0x3057000

19:16:13 Verified /packages/sets/active/boot/os-kernel/if_fxp.ko

19:16:13 /packages/sets/active/boot/os-kernel/if_ixlv1211k.ko size 0x2cb78 at 0x3068000

19:16:13 Verified /packages/sets/active/boot/os-kernel/if_ixlv1211k.ko

19:16:13 /packages/sets/active/boot/os-kernel/ismt.ko size 0x4568 at 0x3095000

19:16:13 Verified /packages/sets/active/boot/os-kernel/ismt.ko

19:16:14 loading required module 'smbus'

19:33:14 -

In this scenario, the device was formatted and re-imaged, but the boot process continued to stall at the same stage. Unlike a typical hardware‑related memory issue, it did not enter a constant boot loop; instead, it simply stopped until the unit was power‑cycled.

Upon checking the fans, we noticed that the trays installed were not the ones intended for this chassis. The installed fans were from a QFX5100 and identified as QFX5100‑FAN‑AFO. These trays are not recognized by QFX5120‑48Y switches, and replacing the device via RMA will not resolve the issue if incorrect fan trays are used.

The correct fan for QFX5120‑48Y model is QFX5110‑FANAFO, as documented in the official data sheet:

https://www.hpe.com/us/en/collaterals/collateral.a00150810enw.html

After replacing the fans with the proper units, the device is able to boot successfully.