[OpenAFS] Migrating existing data onto vice partition on the fly

Levente Peres otravier@gmail.com
Tue, 30 Dec 2014 17:33:44 +0100

On 12/30/2014 05:08 PM, Dirk Heinrichs wrote:
> Am Dienstag 30 Dezember 2014, 16:45:27 schrieb Levente Peres:
>> Hello Jeff,
>> Thank you for answering.
>> I might have been a little obscure... I'll try to clear this up for you.
>> So... Right NOW I have a partition called /vicepa, which exists right
>> now, and has an XFS volume, which is used actively. It has some
>> terabytes of data and about 2.5 times of free space as the actual data.
> Why did you mount it as /vicepa at all? It's not an AFS partition.
I originally wanted to make and AFS server... then I was crossed off,
but some time ago I proved on a smaller scale my point of why I wanted
AFS in the first place (cache and better protocol over WAN to name just
two)... So NOW I get to do it, but... not that comfortably as a bare
installation, you know... that's just how things work here...
>> This data has to be migrated within the same server to AFS.
> Why same server? An AFS setup usually consists of several servers, especially 
> if you want to serve terabytes of data. Not to mention the needed kerberos 
> server.
Same server because I need the transfer to be quick. Once I start - I
need to do the migration in max 1-2 hrs... tops. I know... I know...
>> Unfortunately, I have only this "one" partition remotely big enough to
>> hold the data and/or fast enough to handle in a reasonable amount of time.
> Fast enough for what? To copy over the data or to serve it afterwards?
Both I guess but that's not the main issue, first problem is migrating
it in a very short time. So I need to do it the ugly way, within the
same server... I don't have 8Gb switches or the like and storage fabric
etc to assist me in this externally... simple "work with what you got"
>> My idea was based on the following: Somewhere I remember reading, that
>> it would be OK to have "AFS filesystem data" and "normal files" coexist
>> on the same partition for a while, if I watched carefully not to run out
>> of space. This may or may not be true - it was a long time.
> Yes, it could work, but you should definitely test it on a spare machine first.
Definitely... I will do it on a virtual environment on my home computer
tonight. Hope it will work out... I guess if its OK on small number of
files it should be OK with the big data too... I have backups, but...
better to be sure. I wouldn't have trusted my own tests if I didn't post
to this list for second opinion first, either.
>> So my original concept was that I would create the AFS filesystem on
>> "top" of the "existing data" on the /vicepa partition, then copy it over
>> to the cell's logical mount, then just delete the "old" data and have a
>> "pure" AFS partition left after.
> You should also plan to divide the data into logical chunks that you can store 
> on different AFS volumes (even if you stay on your single server), as it will 
> make backups or migration of your data to other /vicepX partitions (maybe on 
> other AFS servers) easier.
This is definitely worth taking time to think over. I have about a week
to do it so I can give this some thought... thank you for pointing it out.
> HTH...
> 	Dirk