Re: Potential connection loss to CERN AFS cell (retirement of old VLDB servers)

On 1/26/2023 10:18 AM, Diogo Castro ([email protected]) wrote:
>
> In the next week, CERN will turn off the last two original AFS CERN 
> VLDB servers (or rather, the machines using their IP addresses). For 
> reasons related to our network structure and IP allocation, we could 
> not keep the old IPs when retiring the current server generation.
>
> AFS clients still using (only) these IPs will no longer be able to 
> connect to the CERN AFS cell.
>
> We have attempted to get the central CellServDB updated ahead of this 
> change (first with new IPs, then to use (only) DNS for "cern.ch"). 
> However, CellServDB is shipped by various distributions, and anyway 
> only considered at (Linux) client start.
>
CERN sent the requests to update the GRAND.CENTRAL.ORG Public Cell 
Service Database [https://grand.central.org/csdb.html] and OpenAFS 
[https://gerrit.openafs.org/#/c/14842/] in November 2021.   I do not 
believe there is anything more that CERN could have done to prevent end 
user inconvenience.

Thank you for trying.

> How to check whether a particular AFS client is affected:
>
> $ fs getserverprefs -vlservers | grep -E 'afsdb[0-9]+.cern.ch'
>
> - if the output only mentions afsdb1{1,2,3,4}.cern.ch, the 
> configuration is DNS-based and correct - no issues expected.
>
> - if the output mentions a mix of afsdb{1,2}.cern.ch and 
> afsdb1{1,2,3}.cern.ch (the current central CellServDB config), this 
> client will switch automatically to our new servers, possibly after a 
> short hiccup - no major issues expected.
>
> - if the output only has afsdb{1,2}.cern.ch, this client will not be 
> able to connect to CERN.CH in the future.
>
> Our recommendation is to use DNS - CellServDB should have an entry for 
> the cell but no IPs:
>
> >cern.ch                #European Laboratory for Particle Physics, Geneva
>
> />(next cell info here)
>
>
For those that have AuriStorFS clients deployed, graceful transition to 
the afsdb1{1,2,3,4}.cern.ch servers occurred when the afsdb{1,2}.cern.ch 
sites were removed from the published _afs3-vlserver._udp.cern.ch DNS 
SRV record.

Jeffrey Altman