[ale] raid suggestions

[Lightner, Jeff]

Actually good RAID controllers store the RAID set information on the controller AND the disks in the RAID set.  If there is a mismatch the controller's BIOS will tell you and let you decide which is correct.   I've done this more than once here.   Usually it occurs when the battery on the RAID controller fails but in a recent incident we lost a disk but for some reason the hardware didn't detect it as a lost disk - just that it couldn't read RAID SET info from it (it displayed a nice green light but the controller BIOS indicated it was a 0 MB disk which is how I knew it was bad - first time I've ever seen this happen).    It is such mismatches that are the scariest issue because if you just blindly answer you can end up blowing away the RAID set.   We haven't done that on a Linux box yet but I gather our Windows Admins did it at least once.    Note that it isn't something that occurs frequently but with more than 100 servers over a 7 year period though you're going to see it.

Years ago I worked for a company that had about 300 customer sites.   About once every couple of weeks we'd have a site go down for one reason or another and it was always seen as a big deal.   We later signed a customer with over 2000 sites so saw site failures about twice a week.   The President of the company saw me in the elevator and expressed concern about the high rate of failures.  I pointed out that the rate hadn't really increased - just the volume because the number of sites had grown greatly so even at same rate.  Sometimes basic math skills give you the reason with no need for further analysis.   (That reminds me of the Dilbert strip where someone points out the PHB that 40% of absences occur on Mondays and Fridays and the PHB decides he needs to get to the root of the issue while Dilbert is saying "You're joking right?")

________________________________
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Jim Kinney
Sent: Sunday, February 12, 2012 11:59 PM
To: transam at verysecurelinux.com; Atlanta Linux Enthusiasts
Subject: Re: [ale] raid suggestions


Add to it that pretty much ALL hardware RAID is closed proprietary stuff. I can't trust what I can't open and evaluate. And I sure don't like having my feet to the fire for something I really can't fix.

On Sun, Feb 12, 2012 at 11:22 PM, Bob Toxen <transam at verysecurelinux.com<mailto:transam at verysecurelinux.com>> wrote:
On Thu, Feb 09, 2012 at 08:37:03PM +0000, Lightner, Jeff wrote:
> Hardware based (for true RAID) because it doesn't require CPU cycles.
Some hardware RAID controllers store critical information on the
controller.  Thus, a fried controller means all data lost!

This happened about 2 years ago to one of the smartest Linux guys I
know!

Thus, I'll only consider software RAID if it's up to me!

Bob


> -----Original Message-----
> From: ale-bounces at ale.org<mailto:ale-bounces at ale.org> [mailto:ale-bounces at ale.org<mailto:ale-bounces at ale.org>] On Behalf Of Calvin Harrigan
> Sent: Thursday, February 09, 2012 3:26 PM
> To: Atlanta Linux Enthusiasts
> Subject: Re: [ale] raid suggestions
>
> As per a discussion on the list a few months ago, software based raid 10.
>
> On 2/9/2012 2:54 PM, Geoffrey Myers wrote:
> > I've not played with raid stuff of late.  What is the recommended
> > configuration for a small business these days?  Definitely want data
> > protection, but don't want to sacrifice a lot of speed for that purpose.
> >
> > Thoughts?
> >
>
> _______________________________________________
> Ale mailing list
> Ale at ale.org<mailto:Ale at ale.org>
> http://mail.ale.org/mailman/listinfo/ale
> See JOBS, ANNOUNCE and SCHOOLS lists at
> http://mail.ale.org/mailman/listinfo
>
>
>
>
> Athena(r), Created for the Cause(tm)
> Making a Difference in the Fight Against Breast Cancer
>
> ---------------------------------
> CONFIDENTIALITY NOTICE: This e-mail may contain privileged or confidential information and is for the sole use of the intended recipient(s). If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you.
> ----------------------------------
>
>
> _______________________________________________
> Ale mailing list
> Ale at ale.org<mailto:Ale at ale.org>
> http://mail.ale.org/mailman/listinfo/ale
> See JOBS, ANNOUNCE and SCHOOLS lists at
> http://mail.ale.org/mailman/listinfo
_______________________________________________
Ale mailing list
Ale at ale.org<mailto:Ale at ale.org>
http://mail.ale.org/mailman/listinfo/ale
See JOBS, ANNOUNCE and SCHOOLS lists at
http://mail.ale.org/mailman/listinfo



--
--
James P. Kinney III

As long as the general population is passive, apathetic, diverted to consumerism or hatred of the vulnerable, then the powerful can do as they please, and those who survive will be left to contemplate the outcome.
- 2011 Noam Chomsky

http://heretothereideas.blogspot.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.ale.org/pipermail/ale/attachments/20120213/5dff9c97/attachment-0001.html