GSS Redundancy Questions

[g.lynn]

I have inherited a design that utilises 4 GSS devices spread across 2 data centres. Unfortunately the Master and Standby GSS devices are located in the same data centre ! The documentation states that the Master and Standby Sync their config databases. I have several questions arounnd this functionality that don't seem to be clearly documented.

1. Do the other GSS devices contain a copy of this database in memory and is there any way to write this to disk or NVRAM should the primary data centre fail and thus take out the master and standby GSSs?

2. Do the normal GSS devices respond directly to DNS queries using a "cached" DNS database in memory or do they offload the lookup to the Master as this has the current running stored database?

Thanks in advance for any replies.

Regards

Glenn

[burn999]

1. Page (1-9)-(1-10) of the 'Cisco GSS Admin Guide' V1.3 = Logically Removing a GSS or Standby GSSM from the Network.

Don't F with your Primary GSS.

Page 4-28 of the 'Cisco GSS Getting Started Guide' shows you how to cfg a Standby GSSM.

I dont see how to convert a Standby to a 'dummy' or how to promote a 'dummy' to a standby. Maybe its possible, I just haven?t seen it in the docs.

I've never tried it, but I would:

remove your standby and one of you 'dummies' at the second site. Reconfigure the dummy as a standby GSSM and the standby as a dummy. As long as you dont F up your primary this should be low risk and you should have an easy fallback if it goes horribly wrong.

2. Page 1-12 of 'Cisco GSS CLI-based GSS LB Cfg Guide' version 1.3: "Each GSS is known to and sync'ed with the primary GSSM" Read around this quote.

If I were you, I would read the docs thought (all of them) before you try anything.

Note that a subscription to Cisco Networkers Online is only $199 and has some stuff on GSS and lots of other topics. I don?t work for Cisco or anything, but I just listened to the GSS presentation and its pretty good.

Free advice courtesy of Force Networking, Inc.

"Our Kung Fu is the Best"

[g.lynn]

Burn999,

Thanks for your reply. I have read the documentation and it's very ambiguous. I've also read some many of the previous posts on this forum and have deduced that the master and standby GSSMs sync their databases (Postgres SQL I think). There is no mention of any databases on the normal gss devices themselves.

My worry is that a fire could destroy both my master and standby GSSMs and I'll be left without a configuration database as both these devices are presently located in the same data centre! I just need confirmation because I'm pretty sure I'll have to make one of the GSS devices at the secondary datacentre a GSSM-S and demote the current GSSM-S at the primary datacentre. This seem to be the best design choice from what I've read.

Regards

Glenn

[burn999]

I agree the docs are not that great (what happed to cisco?).

I'm also with you that you should make that change.

The docs do indicate that the Master and Standby GSSM have a copy of the database and talk about being able to promote the standby to master while doing maint on the master.

From what I have read and saw at networkers, the GSS (non-gssm) doesnt carry the database in a way that you could recover if you loose both primary and standby GSSM so I see why you would want to be careful.

[g.lynn]

burn999,

Many thanks for your help. It would seem that I'm not the only person confused by the lack of clarity in some of the documentation.

Regards

Glenn

[syediahm]

In the GSS redundancy case, all GSSs in the mesh can answer questions (dns queries) , the redundancy is really only for who has

configuration control of the mesh. Only one GSS (GSS-M) can make changes to all the GSSs at one time.

Whether a device is a GSSM-M, GSSM-S, or a GSS all devices are always processing DNS queries, keepalives, etc. The GSSM-S behaves no differently than a GSS and offers standby for GUI Management in addition to standard functions. Even if there is no GSSM-M configured at a particular time, there will not be any disruption in regards to functionality, aside from the fact that no configuration changes could be made until a GSSM-S is promoted to a GSSM-M.

Thanks

Syed Iftekhar Ahmed

[g.lynn]

Syed,

Thanks for you reply. This explains part of my question.

What I'm trying to determine is whether losing my GSSM-M and GSSM-S in a fire will destroy my configuration database. There doesn't seem to be any mention in the documentation of a Gss device having their own database (locally stored) that is "Synced" with the Master. My own understanding is that should a Gss device be promoted to Standby then it would Sync with the master and would then obtain a copy of the Master's database which would be stored locally (And survive a reboot).

regards

Glenn

[syediahm · Accepted solution]

You are right!

GSSM-M and GSSM-S are the only custodian of database.However each GSS in the network has DNS rules information.

So there are two different updates.

1.GSSM-M send dns information to all GSSs in the GSS-network (including GSSM-S)

2. GSSM-M syncronizes the cofiguration database only with GSSM-S.

If you loose all GSSMs from a GSS network then you will loose the config database.

Its always recommended to backup Gssm database frequently.

Use "gssm backup full" command to backup the database to the Harddisk on GSS and Use either the secure copy (scp) or ftp command to copy or move your full backup to a remote host.

eg.

gssm1.example.com# scp gssfullbk.full server.example.com:~/

hope it helps

Syed iftekhar Ahmed

[g.lynn]

Syed,

Many thanks, it helps a lot. These are exactly the answers I was looking for. It is also as I suspected (I just needed confirmation). I'll need to come up with a migration plan for my GSSM-S. Thanks again.

Best regards

Glenn