Bob Friesenhahn wrote:
> On Thu, 5 Jun 2008, James C. McPherson wrote:
> 
>> Ethan Erchinger wrote:
>>> Hello,
>>> We have a backup strategy that involves mapping LUNs between a given
>>> pair of hosts, and copying data from one of the LUNs (src) and another
>>> LUN (dest).  The src LUNs sit a SAN device, sometimes multiple devices
>>> (zpool mirror).  The src LUN is running a MySQL database and typically
>>> will be running for weeks without issue.
>>
>> I'm sorry, I don't quite understand how this can be a serious
>> "backup strategy" - how on earth did you get to thinking that
>> it was going to work reliably?
> 
> Once again, you show little mercy for the Sun customer.  Is it really 
> wise to beat up customers in public?  It might be limiting to your 
> career path at Sun, or at other companies.  Potential future employers 
> will learn a lot about you via Google.

Hi Bob,
I based my response to Ethan on 5 years of supporting Sun's customers
doing technical escalation resolution (including being a trainer and
Asia-Pacific resource for Sun's implementation of the Kepner-Tregoe
Rational Troubleshooting methodology), bug fixes, alpha- and beta-testing
of new products... all in the storage area. Specifically: storage
device drivers, SANs, MPxIO and backups.

I have also had more than a few years as a software engineer working
on Sun's "leadville" stack, MPxIO and SAS.

If Ethan had logged a call and it came to me, I would indeed be asking
those questions, because to do otherwise would not be providing the
service that was required.


>> So ... _unpatched_ you say? _Why_ ? I know organisations generally
>> have rigorous patching methodologies and schedules, but fer cryin'
>> out loud, S10 Update 4 has been available since the middle of 2007.
>> That's very nearly 12 months old.
> 
> The problem with patching is that it causes down-time.  It sounds like 
> Ethan's application can not afford any down-time and they are doing 
> whatever they can to avoid it.  There is a trade-off between the cost of 
> patching and rebooting the OS, and any the cost of any bugs which may 
> become evident due to not patching.

I'm very, very well aware of what is required to patch a system - both
from the point of view of generating those patches, and from the customer's
perspective. That means schedules, business uptime and outage requirements,
SLAs, patch trains, testing + development environments, rollback,
regression testing... the whole kit+caboodle.

I am also very, very well aware of what can go wrong when a system
is not kept up to date.

My final recommendation to Ethan still applies - he should seek the
assistance of a Professional Services organisation to help him get
a reliable, scalable and supportable backup configuration implemented
for his environment.


James C. McPherson
--
Senior Kernel Software Engineer, Solaris
Sun Microsystems
http://blogs.sun.com/jmcp       http://www.jmcp.homeunix.com/blog
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