# [usb] kernel panic.

## _Flame_

Hi!. I have external usb hdd. If i boot from grub menu very fast then i get kernel panic.

 *Quote:*   

> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown - block (8,21) 

 

If i wait when usb hdd led turn off and sata hdd led turn off too then gentoo boot normally. I use uuid for root parameters and for fstab. Help me please.

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## Sadako

Try adding "rootdelay=10" to your kernel command line in grub.conf, the kernel will boot as normal but wait 10 seconds before trying to mount the root filesystem.

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## _Flame_

 *Hopeless wrote:*   

> Try adding "rootdelay=10" to your kernel command line in grub.conf, the kernel will boot as normal but wait 10 seconds before trying to mount the root filesystem.

 

I tryed even "rootdelay=100", but this don`t help me.   :Sad: 

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## _Flame_

I use kernel param real_root=uuid=...

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