[CentOS] Convert "bare partition" to RAID1 / mdadm?

[m.roth at 5-cent.us]

Benjamin Smith wrote:
> On 07/25/2014 12:12 PM, Michael Hennebry wrote:
>> Is there soome reason that the existing files cannot
>> be accessed while they are being copied to the raid?
>>
> Sheer volume. With something in the range of 100,000,000 small files, it
takes a good day or two to rsync. This means that getting a consistent
image without significant downtime is impossible. I can handle a few
minutes, maybe an hour. Much more than that and I have to explore other
options. (In this case, it looks like we'll be biting the bullet and
switching to ZFS)

Not a big deal. I've done this a number of times, esp when moving a
researcher's home directory, or putting in a larger drive. I rsync it all
over. *Then*, right after it's done, I have them log off, do a final
rsync, and bring it back up. The upshot is that they haven't created
thousands of huge files while the big rsync was taking place, while it was
still up. If I'm really worried, I do a second rsync after the first huge
one, *then* do the "log off and final rsync".

      mark