When you are using VLP, you may be tempted to partition your /dev/sdb disk. After all, you've ran a few commands on your reserved system and it looks like you have an extra disk:
172_29_136_133:~ # sfdisk -s
total: 41943040 blocks
<code>172_29_136_133:~ # df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda2 16281352 2746832 13534520 17% /
udev 506988 96 506892 1% /dev
98631680 89152064 9479616 91% /stage/middleware
1310720 446208 864512 35% /home/u0000653</code>
In this case what you really have is two paths to a single disk. If you partition the second disk /dev/sdb, you will wipe out /dev/sda. This will destroy the root filesystem, a bad thing to do.
As VLP has evolved, we have improved the infrastructure to make it more reliable, but those changes did not keep in synch with the operating systems that we host. So, multipath IO is not enabled in some operating systems. The best course of action in VLP in general is to use the system but do not attempt to alter hardware configuration of the system that you have reserved. We give each user access to root with the understanding that users will use root carefully. But, in this case, even careful Linux root users could get themselves into trouble without this warning about multipath IO.
Be safe! As always, your questions and comments are appreciated.[Read More]