[nycbug-talk] FreeBSD gmirror

Charles Sprickman spork at bway.net
Sun Nov 9 01:48:03 EST 2008

On Sat, 8 Nov 2008, George Rosamond wrote:

> Wondering if anyone has used FreeBSD's geom gmirror for production
> purposes, and what their experiences are.

I've been running it on 2 production servers for some time.  One is a 
fairly heavily used internal box (a kitchen sink type intranet/monitoring 
thing) and the other is a backup mxer + secondary DNS.  One SATA, one 

I have had exactly zero problems with it.

I also have two boxes that will be in production soon running.  One in 
fact because the crappy old Adaptec ZCR card makes it's new, very 
expensive scsi drives only do async transfers - remove ZCR and the same 
SCSI controller does U160.  Gmirror was the only reasonable solution.

Both long time production boxes with it have been tested pretty hard - 
Level3 was trying to rewire the row of cabinets we're in and screwed it up 
for 3 nights in a row, with a total of about 5 unexpected power losses. 
Every damn time the gmirror box came up with no manual intervention.
The other box had a mainboard fry and a disk die.  Again, no malarky to 
deal with.  So far it's been more predictable/stable than most of the 
older Adaptec controllers I deal with.

Performance seems fine to me, at least as good as a mid-level hardware 
RAID card.

> I'm not a fan of software raid, but decided to make the leap, and it's
> been pretty seamless in testing.  I know sometimes there's issues with
> different manufacturer's drives (these are SATA) in one mirror, but it
> tested fine.  I could almost call it a pleasant experience.

I like it because like the good old CCD stuff it is very simple and it 
just works.  Not anything like vinum.

> And no, I'm not running ZFS here. . .
> Another related question, has anyone used geom-based UFS journaling with
> gmirror or on its own?

Try it and let us know. :)  I found too much conflicting info on the combo 
to try it.


> TIA.
> g
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