Two weeks ago my Centos 7 VM that's been running on Google Compute Engine for two years suddenly crashed, serial console log reveals:
[ 1.668426] List of all partitions:
[ 1.669174] No filesystem could mount root, tried:
[ 1.669979] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[ 1.671773] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.10.0-957.27.2.el7.x86_64 #1
[ 1.673630] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 1.675841] Call Trace:
[ 1.676467] [<ffffffffadb64147>] dump_stack+0x19/0x1b
[ 1.677456] [<ffffffffadb5d850>] panic+0xe8/0x21f
[ 1.678455] [<ffffffffae186761>] mount_block_root+0x291/0x2a0
[ 1.679508] [<ffffffffae1867c3>] mount_root+0x53/0x56
[ 1.680619] [<ffffffffae186902>] prepare_namespace+0x13c/0x174
[ 1.681535] [<ffffffffae1863df>] kernel_init_freeable+0x1f8/0x21f
[ 1.684161] [<ffffffffae185b1f>] ? initcall_blacklist+0xb0/0xb0
[ 1.685266] [<ffffffffadb52220>] ? rest_init+0x80/0x80
[ 1.686058] [<ffffffffadb5222e>] kernel_init+0xe/0x100
[ 1.686884] [<ffffffffadb76c37>] ret_from_fork_nospec_begin+0x21/0x21
[ 1.688183] [<ffffffffadb52220>] ? rest_init+0x80/0x80
[ 1.690932] Kernel Offset: 0x2c400000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
I can mount the disk in another instance and read the data. It's only 70% full. Launching the disk in a larger instance produces the same result.
Any suggestions??? Thank you.
Best Answer
I faced the same issue. I was using Centos 7.
I Found that my latest kernel installed crashed causing this.
I managed to login to it with old kernel.
to list the kernel:
#rpm -q kernel
To remove the latest kernel:
#yum remove <kernel-3.10.0-1062.4.3.el7.x86_64>
(replace with your latest kernel)Rebooted machine, installed the new kernel again, all good.
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AFASIK in our case when we did the latest yum update we lost network connectivity part way through and this caused the problem.