Bouncing services to the new machine?

Bouncing services to the new machine?

[Christopher Faylor]

I was thinking of transitioning services to the new system on a
piecemeal basis using something like nc to redirect accesses from one
system to another.

This would obviously introduce a large lag in the connection but are
there other problems with that?  I'm just a little concerned that I've
forgotten some esoteric thing on the new system which will inconvenience
people when I bring it online.  If I redirect things in this way, I'll
be able to fall back to the old system quickly if the new system screws
up.

I could redirect mail, ftp, and http, I think.  non-anon-cvs would be
problematic since it relies on ssh.

Anyone ever done anything like this?  Bad idea?  Good idea?

cgf

Re: Bouncing services to the new machine?

[Ian Lance Taylor]

Christopher Faylor <cgf@redhat.com> writes:

> I was thinking of transitioning services to the new system on a
> piecemeal basis using something like nc to redirect accesses from one
> system to another.
> 
> This would obviously introduce a large lag in the connection but are
> there other problems with that?  I'm just a little concerned that I've
> forgotten some esoteric thing on the new system which will inconvenience
> people when I bring it online.  If I redirect things in this way, I'll
> be able to fall back to the old system quickly if the new system screws
> up.
> 
> I could redirect mail, ftp, and http, I think.  non-anon-cvs would be
> problematic since it relies on ssh.
> 
> Anyone ever done anything like this?  Bad idea?  Good idea?

I personally wouldn't recommend using nc.  For most services you can
just redirect.  For mail, you can redirect using MX records.  For HTTP
you can redirect using permanent redirection commands in http.conf.
For ftp, make people use ftp.sourceware.org, and change that.

Perhaps this would be a good time to use different names for different
services, to make any such change simpler in the future.

Ian

Re: Bouncing services to the new machine?

[Jason Molenda]

On Fri, Jan 10, 2003 at 01:58:39PM -0500, Christopher Faylor wrote:
> I was thinking of transitioning services to the new system on a
> piecemeal basis using something like nc to redirect accesses from one
> system to another.

I think you meant this, but if any of the services get moved, all
of them must be moved--nearly everything is interconnected in some
way or another.  For instance, if the canonical mail server/web
archiver/web server becomes the newsystem, ftp also has to go
because some mail archives in ~ftp are updated as mail notes come
in.  And the project sources have to be over there because the mail
archive staging area is in the same place as the cvs repository,
so anoncvs and ssh cvs have to go.  And if cvs is there, then the
cvs log essage -> gnats thing doesn't work reliably unless gnats
is there.

When we did the last switch, we renamed the old system to
cruftware.cygnus.com and dropped the new sourceware.cygnus.com into
place.  If we'd screwed up some how, we could copy over the changed
bits from sourceware to cruftware and swap them back.  (luckily
that never happened ;)

I don't want to say that redirecting is necessarily doomed, but it's
going to be tricky to have one system be the canonical source of some
files and the other system be the canonical source of other files, and
keep them all in correct synchornization..

J

Re: Bouncing services to the new machine?

[Angela Marie Thomas]

> I don't want to say that redirecting is necessarily doomed, but it's
> going to be tricky to have one system be the canonical source of some
> files and the other system be the canonical source of other files, and
> keep them all in correct synchornization..

Especially when they're 3000 miles apart.

I also remember the last switch being all-or-nothing.

--Angela

Re: Bouncing services to the new machine?

[Jonathan Larmour]

Angela Marie Thomas wrote:
>>I don't want to say that redirecting is necessarily doomed, but it's
>>going to be tricky to have one system be the canonical source of some
>>files and the other system be the canonical source of other files, and
>>keep them all in correct synchornization..
> 
> 
> Especially when they're 3000 miles apart.
> 
> I also remember the last switch being all-or-nothing.

Personally I'd prefer well advertised down time and a "proper" switch to 
something risky that may cause things to go horribly wrong.

Jifl
-- 
eCosCentric       http://www.eCosCentric.com/       <info@eCosCentric.com>
--[ "You can complain because roses have thorns, or you ]--
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Re: Bouncing services to the new machine?

[Christopher Faylor]

On Fri, Jan 10, 2003 at 08:35:37PM +0000, Jonathan Larmour wrote:
>Angela Marie Thomas wrote:
>>>I don't want to say that redirecting is necessarily doomed, but it's
>>>going to be tricky to have one system be the canonical source of some
>>>files and the other system be the canonical source of other files, and
>>>keep them all in correct synchornization..
>>
>>
>>Especially when they're 3000 miles apart.
>>
>>I also remember the last switch being all-or-nothing.
>
>Personally I'd prefer well advertised down time and a "proper" switch to 
>something risky that may cause things to go horribly wrong.

Ok.  If we're going to get into the use of alarmist adverbs then I think
I have all of the feedback I can take right now.

No more input is required.

cgf

Re: Bouncing services to the new machine?

[Benjamin Kosnik]

On Fri, 10 Jan 2003 13:58:39 -0500
Christopher Faylor <cgf@redhat.com> wrote:

>I could redirect mail, ftp, and http, I think.  non-anon-cvs would be
>problematic since it relies on ssh.

What would you say to redirecting non-anon-cvs to the new machine first,
say this sunday (2003-01-12) or next (2003-01-19), then say the mailing
lists, then http? I would think that anon-cvs and ftp could be brought
in line later, and perhaps the old server can just stick with these
anyway?

Good idea?

-benjamin