[OpenAFS] Client update and failover for afsdb hosts

[Steve Simmons]

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To make a long story short, we're going to be moving the network on which
our afsdb servers reside from one data center to another. Trust me, you
don't want to know the details. This will required a period of time wherein
all the current afsdb hosts are down. The fileservers will not be affected.

To minimize the pain during the transition, we're temporarily adding a
fourth non-voting server and updating CellServDB files appropriately. Some
questions have come up about how the clients will react to this change and
the best strategy to pursue for them. Complicating this are clients running
various versions of openafs, most of which are recent 1.6/1.8, but there
are a few 1.4.14/15 clients out there. All the clients referred to here are
running various flavors of Linux. Yeah, I could read the code  for all
those versions, but in case someone happens to know:

Does a client read the CellServDB only at startup? Can it be forced to
re-read it without a restart?

If a CellServDB contains multiple entries (4) for a given cell, does the
client process them in any particular order (round robin, random, other)?
If some are non-responsive, will the client give preference to the others?

Advance thanks,

Steve Simmons

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<div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-family:arial,he=
lvetica,sans-serif">To make a long story short, we&#39;re going to be movin=
g the network on which our afsdb servers reside from one data center to ano=
ther. Trust me, you don&#39;t want to know the details. This will required =
a period of time wherein all the current afsdb hosts are down. The fileserv=
ers will not be affected.<br><br>To minimize the pain during the transition=
, we&#39;re temporarily adding a fourth non-voting server and updating Cell=
ServDB files appropriately. Some questions have come up about how the clien=
ts will react to this change and the best strategy to pursue for them. Comp=
licating this are clients running various versions of openafs, most of whic=
h are recent 1.6/1.8, but there are a few 1.4.14/15 clients out there. All =
the clients referred to here are running various flavors of Linux. Yeah, I =
could read the code=C2=A0 for all those versions, but in case someone happe=
ns to know:</div><div class=3D"gmail_default" style=3D"font-family:arial,he=
lvetica,sans-serif"><br>Does a client read the CellServDB only at startup? =
Can it be forced to re-read it without a restart?<br><br>If a CellServDB co=
ntains multiple entries (4) for a given cell, does the client process them =
in any particular order (round robin, random, other)? If some are non-respo=
nsive, will the client give preference to the others?<br><br>Advance thanks=
,<br><br>Steve Simmons</div></div>

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