当我们从AMI启动实例时.首先可以访问实例(ssh).一旦我们停止/启动实例或重新启动它,机器就会通过ssh无法访问,我们可以ping它.我们在系统日志中看到以下错误.

AMI ID used - ami-72dc9220
Instance - i-0896a15f - 

Linux rhel6.4 M1.large instance.
../

******************* BLKFRONT for device/vbd/2049 **********
backend at /local/domain/0/backend/vbd/236/2049
Failed to read /local/domain/0/backend/vbd/236/2049/feature-barrier.
Failed to read /local/domain/0/backend/vbd/236/2049/feature-flush-cache.
14680064 sectors of 512 bytes
**************************
Thread "kbdfront": pointer: 0x21e0130010,stack: 0x3720000
FBFRONT for device/vfb/0 **********
KBDFRONT for device/vkbd/0 **********
Failed to read device/vfb/0/backend-id.
Failed to read device/vkbd/0/backend-id.
Error ENOENT when reading the backend path device/vkbd/0/backend
Thread "kbdfront" exited.
Error ENOENT when reading the backend path device/vfb/0/backend

./

解决方法

能够解决这个问题.这是由于
a bug from REDHAT for 6.4 rhel instances.

从AMI启动机器后,连接到机器并切换到root用户,并在下面更改/etc/rc.d/rc.local文件…

删除以下三行并保存文件：

cat <<EOL >> /etc/ssh/sshd_config 
UseDNS no 
PermitRootLogin without-password
../

还应该从/ etc / ssh / sshd_config文件中删除垃圾条目.

在这些更改工作正常后,机器重新启动.