[GRLUG] Raid, LVM, and Cheap Storage

[Bruce Smith]

> Only blown filesystem
> I've ever had was a ReiserFS - that was simple, don't use ReiserFS.

Maybe Hans can fix that, if they let him have a computer in his cell.
He'll definitely have lots of free time, for the rest of his life!  ;-)

>> Raid Controllers:
>> My experiences with raid controllers and their interfaces vary.  Many
>> raid controllers have batteries on the controller itself, so in the
>> event of a hardware failure the controllers buffer can be cleared and
>> the raid array will not be damaged by incomplete writes.
>> My experiences with rebuilding Raid arrays or restoring data from a
>> crashed raid array are all painful.
>> Does anyone have a good story or know of technologies that allow you
>> to move hardware or a portion of a raid array to restore data on a
>> different piece of non-identical hardware in the event of a server
>> failure?
>
> No, that can't be expected to work.  RAID insulates you from failures of
> individual drives, and nothing else.

Put a good UPS on your systems, and bring down the systems cleanly
when an outage is detected (or have a generator along with your UPS)
to prevent power outage crashes.

>> 2.) The only way of detecting a disk failure at a remote site is for
>> someone to notice there is a 'red' or 'amber' light on.
>> 3.) No one monitors system voltages
>> 4.) No one monitors system temperatures.
>
> OpenNMS! <http://www.opennms.org/index.php/Main_Page>  I guarantee if
> the above have to be done manually, it just won't happen.

Can OpenNMS detect a failed disk in an array?

>> 5.) No one performs read / access tests or write tests or head tests -
>> if this is just done once a year you can almost always predict a drive
>> failure.
>
> SMART will do this automatically on current systems.

Can SMART monitor drives that are members of an array?

I was under the impression it couldn't, because the OS only sees the
virtual disk, not the individual drives.  (but I never tried either)
Ditto for SMART above.

>> Now I've pointed out all of the short sightedness I've experienced in
>> my journeys - I'm sure the Linux IT community being as informed as it
>> is will not be among these organizations I speak of - so I'll be
>> interested to hear about your experiences and setups and uses of linux
>> technology to come up with unique and cost effective storage
>> environments.
>
> We've recently started scrapping out all our old hardware and
> consolidating on VMware ESX on a pair of Silicon Mechanics servers
> connected to an EMC SAN via iSCSI.  Myriad physical servers is too much
> of a maintanence burden, too hot, and too inflexible.  This frees up IT
> to focus on interesting/useful problems.

VMware is great for combining old hardware, especially servers with
low resource requirements (like Linux firewalls).

And VMware ESXi Server is now FREE of charge!  :-)

 - BS