[nycbug-talk] FreeBSD gmirror

Isaac Levy ike at lesmuug.org
Sun Nov 9 02:00:37 EST 2008

> On Nov 8, 2008, at 9:04 PM, George Rosamond wrote:
>> Wondering if anyone has used FreeBSD's geom gmirror for production
>> purposes, and what their experiences are.

Sortof- I ran into gmirror for a small emergency, where the disks were  
both failing on a box I'd never touched before and did not build to  
begin with.

Noteworthy:  In my case, a rare case, I needed physical access to at  
the very least, unplug the failing drive, so I could see straight (I  
had to try booting the box on each drive until it came back up).
In this instance, I would even hang before the filesystems were being  
loaded, so it was impossible to troubleshoot from a running system.
The failure I was experiencing was intermittent on one drive,  
S.M.A.R.T didn't catch it even...  But this scenario could have  
happened with hardware RAID, so...

Regardless, I was impressed that with a bit of quick reading, I could  
simply 'turn off' the Geom Mirror, modify the fstab, remove the bad  
drive- and Viola, the drive booted as a UFS drive like normal.  *Very*  
cool- saved the day in fact.  Client chose to get a second server for  
backups instead of making a new gmirror (tiny office).

I was simply impressed with how clear gmirror was to use, especially  
in a pinch.

On Nov 9, 2008, at 12:32 AM, Dan Langille wrote:

> Production?  Define please.
> I'm using gmirror on my gateway at home, my development box at home,
> and soon my workstation at the office.

I think George is deploying internet-facing servers, (vs desktop use  
or something), just because I believe I know what he's up to with  
these boxes.  Actually, because of physical proximity, production is a  
term I use mostly for servers- workstations/desktops have human  
contact, and therefore different expectations- (a user can push the  
button, etc...)

It's not a bad question though, in the context of mirroring, physical  
access could play an important role with some RAID schemes- etc...

Ya know, without an ounce of sarcasm, I truly would love to hear the  
definition of 'Production' from others- (or hammer it out on list).

To me, Production tries to label a given software or hardware as  
proven not to:

- Not fail in ways which take food of my plate (at work)
- Not fail in ways which are unexpected
- Not fail in ways which make me cry (at home)
+ Be Reliable/Proven/Stable/Trusted software in an assumed or given  

Hard metrics aren't always part of Production criteria, (e.g. how many  
days uptime will it have?  etc...)

Although some organizations I've been in have stiff/formal criteria  
for 'Production' systems, and I've even created this formal criteria,  
it's always based on context.  Any good QA person will explain that  
context is critical to assessment...
Threat models, business models, usage patterns, and applied value- all  
affect the meaning of Production.

Wikipedia is a blank:


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