CentOS - Mar 2011 - {OT] Re: Installing IMA (Integrity Measurement Architecture) on CentOS 5.5

Greetings,

On 3/24/11, Akemi Yagi <amyagi at gmail.com>
wrote:
>  I should note, however, that they are not for production use.
>
> Akemi

Thanks Akemi very much for your always relevant and brilliant works.

</rant>
As an Indian, where "veda" repository of knowledge originated, I have
always looked at every member of this list as a repository of
knowledge.

http://en.wikipedia.org/wiki/Vedas


I am presuming you are of Japanese origin. together India and Japan
have had a very, very long shared history indeed :
http://www.ece.lsu.edu/kak/VedicJapan.pdf

I stand in awe in front of the giant of the members fo this list.

i am almost about to rollover to the so-called "golden" age of 50,
(the origin of these jubilees of which I am unaware of) My respectful
namo namaH  (in ITRANS encoding) to all the members.

I am sure you have heard of Hanuman from Ramayana the best grammarian known?

</rant>

Having said that, I have this troubling thought for last decade: What
exactly is high availability: is it 24/7 power on time? or is ti "when
needed". Please not it am not talking about the maybe arrogant  "on
demand" attitude of a human.

I have been a member of this, linux-cluster, and other lists for
alomst half a decade.

I have managed a two node Hearbeat/DRBD setup for about 2 years which
was transformed into a two-node (which became a three) node RHCS
cluster at least for about two Quarters.

This under extreme circumstances in India like 4 hours of (Electrical
Power Load Shedding) outage every day with no fencing device.

I can claim I at least tried that mating dance with those two beasts
and (horror of horror) the breeding ground of PHB (vnbrims.org) with
about 200 PHB without any significant assistance.

I never understood the term "Hig Availability" : does it mean
available as in "soliciting" ?

What exactly those lusers want? and what exactly we self declared high
tech droids / engineers seek?

What exactly is "production" use? (I know DEV, UAT, blah, bla,  tla
etc been there done that and I don't have the T shirt - nobody gave me
one)

Always with warm regards only,

Rajagopal

On 3/24/2011 2:48 PM, Rajagopal Swaminathan wrote:
>
> I never understood the term "Hig Availability" : does it mean
> available as in "soliciting" ?
"High Availability" means that you are pushing toward 100% uptime for
your services.  You try to make sure that no one event can take you down.
> What exactly is "production" use? (I know DEV, UAT, blah, bla, 
tla
> etc been there done that and I don't have the T shirt - nobody gave me
> one)
"Production use" basically means that you are using the
software/hardware/whatever in a situation where you are relying on it. 
In other words, not in a development, testing, or other non-critical
application.  The best example of "Production use" is a company's
main
website or mail server.

-- 
Bowie

Rajagopal Swaminathan wrote:
> On 3/24/11, Akemi Yagi <amyagi at gmail.com> wrote:
>>  I should note, however, that they are not for production use.
<snip>
> </rant>
<snip>
> I am sure you have heard of Hanuman from Ramayana the best grammarian
> known?
>
Huh - it's been more than half a lifetime since I read a translation of
the Ramayana, or maybe it was the translation, but I don't remember
Hanuman as grammarian. <g>
> </rant>
>
> Having said that, I have this troubling thought for last decade: What
> exactly is high availability: is it 24/7 power on time? or is ti "when
> needed". Please not it am not talking about the maybe arrogant 
"on
> demand" attitude of a human.
Ok, h/a is not "fault tolerance", which is for 99.+% uptime (and you
*pay*
a lot for additional decimals there). What it is for is well over 90%
uptime, though where I've worked, including supporting the City of Chicago
911 system (emergency system, that is), it was expected to be over 99%
uptime. h/a, as you should be familiar from your experience, two or more
servers share an asserted IP address, and if one server goes down, another
will see within whatever's configured - 30 seconds, maybe - the other
server then asserts the IP address, and offers all of the services
expected. They should also be sharing redundant storage, so that the only
thing that should be lost are transactions that were just started when the
first server went down; those that were partly transacted should be rolled
back to a known state when the second server asserts the
IP.
>
> I never understood the term "Hig Availability" : does it mean
> available as in "soliciting" ?
Nope - it has real meaning.
>
> What exactly those lusers want? and what exactly we self declared high
> tech droids / engineers seek?
>
> What exactly is "production" use? (I know DEV, UAT, blah, bla, 
tla
> etc been there done that and I don't have the T shirt - nobody gave me
> one)
All services expected from a server at a given IP should be available up
to or over 99% of the time, with no lost transactions, or transactions in
an undefined state - that's h/a and production.

         mark

> -----Original Message-----
> From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On
> Behalf Of Rajagopal Swaminathan
> Sent: Thursday, March 24, 2011 14:49
> To: CentOS mailing list
> Subject: [CentOS] {OT] Re: Installing IMA (Integrity Measurement
> Architecture) on CentOS 5.5
> 
> Greetings,
> 
> Having said that, I have this troubling thought for last decade: What
> exactly is high availability: is it 24/7 power on time? or is ti "when
> needed". Please not it am not talking about the maybe arrogant 
"on
> demand" attitude of a human.
> 
You probably don't want it to be your only reference, but in my opinion
Wikipedia has a pretty good first pass definition of high availability
[1] means between you and your boss, i.e., "...a prearranged level of
operational performance will be met during a contractual measurement
period."
> This under extreme circumstances in India like 4 hours of (Electrical
> Power Load Shedding) outage every day
So have you and your boss prearranged a "level of operational
performance will be met during a contractual measurement period"?
Something like: The system will be available to the users in the
building 90% of the time when the local power grid is powered up?


[1] http://en.wikipedia.org/wiki/High_availability

On Friday, March 25, 2011 03:35:29 pm Les Mikesell
wrote:
> If 'get there' is defined as all redundant copies being in a
consistent
> state, then you'll fail at this point in transactional mode in the 
> fairly likely event that you have a network blip between the db master 
> and slave(s) or one of them is down. 
Puh-lease.  TCP has solved that problem; look into the new algorithms and
techniques PostgreSQL 9 brings to the ACID table.

Networks at layer 3 are expected to blip; TCP at layer 4 makes it a reliable
stream.  Or if it goes down both endpoints know it went down, and the database
engine has a choice whether to abort and rollback or wait on a retry.  Replay
write-ahead logs are another way to deal with this.