🚀 go-pugleaf

"Leythos" <void@nowhere.com> wrote in message
news:MPG.1aa87949bcd9db2398a26e@news-server.columbus.rr.com...
> In article <403ea6bb$0$19707$afc38c87@news.optusnet.com.au>, miro01
> @hotmail.com says...
> > I once spoke to a very sad IT manager. He had a mirror setup for his
boot
> > drive. When the main drive started to wig out and write garbage the RAID
> > controller obliged by writing garbage to the mirror. Thus killing both
boot
> > disks.
>
> Your very sad IT manager was ill informed - the RAID controller controls
> what is WRITTEN to the drive, not the drive itself. Your statement that
> the drive started wigging out and corrupted the other drive is bogus.

Even that isnt necessarily true. You would have to know whether the drive
had come into a situation that it shouldnt have, causing damage elsewhere.
Eg, throw a wrench in moving gears and strange thigns happen!

> What happens is that the RAID controller goes bad and takes out both
> drives. I have seen RAID controllers go bad and take out all drives
> data, not the drives, just the data, but I've yet to see a bad drive
> take out the other drives.

It's called "The FZZZST Principle". Sometimes a drive dies in ways most
people never ever get to personally see. However, it still doesnt really
explain that sentence I posed in that other letter.

>
> I think if you talk with IT managers around the country you'll find that
> they would rather have a MIRRORED OS Boot drive than not have one. Think

Yeah that may well be true. I still keep thinking of the "virus that got in"
being mirrored though! :)

> about it, without a redundant drive you loose everything if the single
> drive dies - not the data on the other drives/arrays, but it takes time

No, not necessarily. Even Powerquest sell Drive Image 7 in a version that
allows hourly incremental backup. This is, in fact, my personal preference.
Eg, 9AM tomorrow morning the incremental gets done and at 9:30AM a virus
gets in and wipes all the much needed data. What the company has lost is 30
minutes of work. Now depending on the company, that may not be a great loss.
Even in companies that WOULD consider that a great loss in some areas, there
are others where it wouldnt be.

> to rebuild the OS, reapply security settings, etc... With a mirror you
> just swap out the bad drive and you are still up and running, not even
> any down time in the case of SCSI or SATA based systems.
>

No, with a proper mirrored array, your C goes down and the mirror takes
over. You fix C and put it back online and the other drive then becomes the
backup again, all done without interrupting work flow. Of course this DOES
depend on the nature of what caused C to die.

> As for your database comments, I've managed and designed MS SQL
> databases with sizes from 20gb to 750gb, with a current one expected to
> hit 1.2tb later this year. Write caching on the controller is not a
> problem for the drives, that why a good card will have a battery and
> NVRAM, the drives don't know anything, they are dumb devices, it's the
> controller that does all the work. Even the database doesn't know it's a
> RAID array, it only knows that there is a bus to pull/feed data from/to.
>

Admittedly more than I have done!