I always had ipv6 tunneling enabled on my server. One with he.net and one with 6to4. I never had any problems with them with either as a default route. Recently my server provider linode.com start supporting native IPv6, but I found out other IP addresses are not route-able through native interface. Linux is only smart enough to pick which source address to use for outgoing connection, but not so much about return path.
The solution is policy based routing with IPv6. There are two related options in kernel configure, so make sure they are enabled. If not, you will encounter an error.
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There is problem which has been puzzled me for long time. When the grub2 root is on 2nd disk, the stage2 is not directly bootable from grub4dos stage1, but can be chain loaded from grub4dos as a linux kernel. The same problem happens to burg as well.
It turns out the stage2 file only has the relative path from root if you use grub-install script. So all you have to do is to embed a absolute path in prefix. Here is the brief step to make a direct bootable stage2.
There are many commands to copy a directory in Linux. The difference between them in current Linux distribution are very small. All of them support link, time, ownership and sparse.
I tested them to copy a Linux kernel source tree. Each command I tested twice and keep the lower result. The original directory size is 639660032 bytes. All methods generate exact same size of 675446784 bytes without sparse option.
rsync -a src /tmp
rsync -a -S src /tmp
find src -depth|cpio -pdm /tmp
find src -depth|cpio -pdm –sparse /tmp
cp -a –sparse=never src /tmp
cp -a –sparse=always src /tmp
tar -c src|tar -x -C /tmp
tar -c -S src|tar -x -C /tmp
Time used and destination size:
Concolusion: For non sparse copy, rsync is the fastest. For sparse copy, rsync and cpio have the best space efficiency, but slow.