[OpenAFS] AFS design question: implementing AFS over a
highly-distributed, low-bandwidth network
Mon, 19 Jan 2009 18:22:36 -0800
So, in your considered opinion, would it be wiser to go with one cell, put =
up with potential quorum snafus, ensure the clients set their preferred =
server to a local one, and move R/W volumes when users move locations? Or =
to go with multiple cells, perhaps one as master, and resolving =
ambiguities on a per-volume basis depending on how that volume is intended =
to be used?
> -----Original Message-----
> From: jaltman=40secure-endpoints.com
> Sent: Mon, 19 Jan 2009 19:02:59 -0500
> To: clc31=40inbox.com
> Subject: Re: =5BOpenAFS=5D AFS design question: implementing AFS over a
> highly-distributed, low-bandwidth network
> Chaz Chandler wrote:
>>>> 2) There is no good AFS-based solution for group shares in this
>>> i don't agree with that, but it depends on your interpretation.
>> Ah, good. What would you recommend?
> The problem you are facing is that OpenAFS does not support read-write
> replication. There can only be one instance of a read-write volume at a
> time. If your model is
>>>> Further questions:
>>>> a) What is the best way to replicate a volume across cells?
> There isn't a defined mechanism for this and doing so can create some
> problems specific to the attempt to do so. As far as each OpenAFS cell
> is concerned the volumes are not replicas. If modifications are made in
> multiple cell instances they will diverge. It is possible to use one
> cell as a master and from that cell dump volume images that can then be
> pushed into other cells. However, they should be treated as readonly in
> the alternate cells.
>>>> b) How would the presence of multiple cells effect the krb5
>>>> infrastructure (currently: one realm, one cell, cell name =3D realm =
>>>> internal LAN domain name)?
>>> it doesn't have to be. you can have many cells in a realm, for
>>> instance, the sipb.mit.edu, athena.mit.edu, etc cells in the
>>> ATHENA.MIT.EDU realm.
>> True, but is it as simple as adding an afs/newcell=40REALM principle and
>> making sure the
>> users get tokens for all cells?
> Yes. On Windows the Network Identity Manager provider and/or the
> OpenAFS integrated logon network provider will permit you to automate
> this for your users.
>>>> c) Are any of the Morgan Stanley volume management system utilities
>>>> available publicly, or are their methods sufficiently documented
>>>> publicly? All of what I've read about them are from previous
>>> as far as i know none of their tools are distributed at this time.
>> Anyone know any Morgan Stanley folks with whom I could chat about this
>> stuff? Is this
>> something others would be interested in as well?
> In my opinion, the Morgan Stanley tools are not general purpose. They
> do what they do but are very specific to the way that Morgan Stanley
> built their infrastructure.
> Jeffrey Altman
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