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Re: to lvm or not to lvm?

On Tue, 2007-05-01 at 10:39 +0800, Bob wrote:
> Andrew Sackville-West wrote:
> 8< snip lots of automatically growing partitions using LVM stuff
> > Why are you after this complexity of automatically growing partitions?
> > disk space is cheap. recovering from problematic fs resizes is NOT. I
> > understand the idea of tuning your partition sizes so that you can
> > have the optimal size and this is very doable with LVM, but if you've
> > got portions of your directory tree that might grow really big, then
> > just give them the space and be done with it. It you later determine
> > that you don't need it all, you can adjust then with LVM with relative
> > ease. 
> >   
> I'm trying to think of a way an admin coming for the Windows world, or 
> from a home server world, where they've had the convenience of not 
> having to think about these things and you've either got harddrive space 
> or you don't, can have a that convenience while retaining the extra 
> security of having lots of partitions with different functions that 
> can't steal space from each other.  I don't know how common it is for a 
> live fs resize to go south, if it's a statistically significant 
> percentage then obviously it wouldn't be worth the risk, if not I still 
> think it's a good idea.

Think about this then. LPARs on an IBM machine. LPAR allows you to
"redistribute" processors and memory to logical machines. The hypervisor
gives you the ability to "add processing power" to a logical machine or
"add memory" or to remove them.

This give you flexibility to control your "domains" and flow the
resources depending on your needs. Then think about doing LVM with those
guys. Sure does throw a monkey wrench in thinking about that.

As far as resizing, AIX has been doing it for years, both resizing
larger and resizing smaller. Though the "growing" is much more tested,
the shrinking does works well.

> > And if your logs are getting so big, then you need to look into other
> > solutions: do you really need all the stuff you are logging; are you
> > using logrotate; is there some problem that is spewing out errors into
> > your logs etc etc etc.
> >   
> It's not a problem for me at the moment, I'm just mulling the ideas 
> round, if it's a service that might be useful I might try and write it.

Make sure you look around well, no need to re-spec the wheel. If you
feel the need to write something, use a well done exisiting spec to
write from. Life is so much easier with a well written spec.

> > that said, you may of course do whatever you like to your system. And
> > the idea sounds cool on the face of it. I just think you're asking for
> > trouble and unneeded complexity. 
> >   
> I agree simplicity=good complexity=bad, but sometimes it's worth adding 
> two measures of complexity to an automated system in order to remove one 
> from user, or in this case admin, space, particularly if you can do it 
> in a relatively easy to understand way, such as with well documented 
> shell scripts, getting called by a disk space monitoring daemon.

Auto adding of space has been done. Trust me on this one. Don't do it.
I've seen the after effects. A typo in a script can do more harm in 20
seconds (or less) than any one person could do in 20 years when dealing
with disk space. You would be well advised to setup an existing projects
disk space monitoring system and have it urgently mail you that disk
space is becoming a premium commodity on /blah filesystem.

> Anyway, I've got so many projects on at the moment I probably won't have 
> time to do anything about it, it's fun to kick the ideas round though.

Even a better to use someone else's work. ZENOSS http://www.zenoss.com/

Works wonders. It has beaten HP's OpenView and IBM's Tivoli regularly
outperforming them and delivering better flexibility and presentation of

> -- 
> Garrr, do your bit for global warming, become a pirate, you can "borrow" my copy of Windows 95 if you want.
greg, greg@gregfolkert.net

Novell's Directory Services is a competitive product to Microsoft's
Active Directory in much the same way that the Saturn V is a competitive
product to those dinky little model rockets that kids light off down at
the playfield. -- Thane Walkup

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