[OpenAFS] Potential connection loss to CERN AFS cell (retirement of old VLDB servers)

Diogo Castro diogo.castro@cern.ch
Thu, 26 Jan 2023 15:18:03 +0000


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(This is a site-specific operational issue but we hope to give other AFS si=
te admins a heads-up for any user support issues. Apologies if you are not =
concerned at all.)

Dear all,

In the next week, CERN will turn off the last two original AFS CERN VLDB se=
rvers (or rather, the machines using their IP addresses). For reasons relat=
ed to our network structure and IP allocation, we could not keep the old IP=
s 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 chang=
e (first with new IPs, then to use (only) DNS for "cern.ch"). However, Cell=
ServDB is shipped by various distributions, and anyway only considered at (=
Linux) client start.


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 automa=
tically 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 t=
o 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)

Regards,
Diogo Castro
on behalf of the CERN AFS service

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<p class=3D"MsoNormal">(<span lang=3D"EN-US">T</span>his is a site-specific=
 operational issue but we hope to give other AFS site admins a heads-up for=
 any user support issues. Apologies if you are not concerned at all<span la=
ng=3D"EN-US">.</span>)<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">Dear all,<o:p></o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US"><o:p>&nbsp;</o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">In the next week</span>, CERN w=
ill turn off the last two original AFS CERN VLDB servers (or rather, the ma=
chines using their IP addresses). For reasons related to our network struct=
ure and IP allocation, we could not
 keep the old IPs when retiring the current server generation.<o:p></o:p></=
p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">AFS clients still using (only) these IPs will no lon=
ger be able to connect to the CERN AFS cell.<o:p></o:p></p>
<p class=3D"MsoNormal">We have attempted to get the central CellServDB upda=
ted ahead of this change (first with new IPs, then to use (only) DNS for &q=
uot;cern.ch&quot;). However, CellServDB is shipped by various distributions=
, and anyway only considered at (Linux) client
 start.<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">How to check whether a particular AFS client is affe=
cted:<o:p></o:p></p>
<p class=3D"MsoNormal">$ fs getserverprefs -vlservers | grep -E 'afsdb[0-9]=
+.cern.ch'<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">- </span>if the output only men=
tions afsdb1{1,2,3,4}.cern.ch, the configuration is DNS-based and correct -=
 no issues expected.<o:p></o:p></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">- </span>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 serve=
rs, possibly after a short hiccup -
 no major issues expected.<o:p></o:p></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">- </span>if the output only has=
 afsdb{1,2}.cern.ch, this client will not be able to connect to CERN.CH in =
the future.<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal">Our recommendation is to use DNS - CellServDB should=
 have an entry for the cell but no IPs:<o:p></o:p></p>
<p class=3D"MsoNormal">&gt;cern.ch&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp=
;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; #European Laboratory for =
Particle Physics, Geneva<o:p></o:p></p>
<p class=3D"MsoNormal">/&gt;(next cell info here)<o:p></o:p></p>
<p class=3D"MsoNormal"><o:p>&nbsp;</o:p></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">Regards,<o:p></o:p></span></p>
<p class=3D"MsoNormal"><span lang=3D"EN-US">Diogo Castro<o:p></o:p></span><=
/p>
<p class=3D"MsoNormal">on behalf of the CERN AFS service<o:p></o:p></p>
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