[DRBD-user] Problem setting up drbd 8.0

Lars Ellenberg Lars.Ellenberg at linbit.com
Thu Jan 25 22:15:57 CET 2007


/ 2007-01-25 17:18:53 +0100
\ Martin Bene:
> As a longtime user of drbd versions 0.5.6 through 0.7.22 I thought I
> wouldn't have much of a problem setting up 8.0 on a new cluster.
> 
> Wrong.
> 
> Mostly I think that I'm running into a lack of documentation, and thus
> making stupid mistakes in setup.

we are working on more on documentation now...
so that should improve "soonish" :->

> Desired config: two drbd devices on software raid with internal metadata
> for use inprimary/secondary config.
> 
> * Info that meta data needs to be created as a seperate step is fairly
> sparse.

right.

> * startup script for gentoo is somewhat minimalistic- any special reason
> the script does _not_ load the drbd  module?

well. we don't gentoo. I never even looked at that script,
its been some user contribution.

> So far I've created the md devices I want to run drbd on, and created
> drbd meta data on the devices.
> 
> Kernel is 2.6.19

hopefully not. 2.6.19 is corrupting data...
2.6.19.2 might be a better one?

btw, since you do drbd on md raid, did you notice
 http://thread.gmane.org/gmane.linux.raid/14142/focus=14142

the impact on initialization time for drbd 8 is
neglectable (the mentioned improvement is for drbd 0.7),
but it is probably still noticeable
if you have latency-bound workloads.

> Trying to start drbd results in an error:
> 
>  * Starting DRBD ...
> Failure: (115) Meta device is already mounted.
> Command '/sbin/drbdsetup /dev/drbd0 disk /dev/md3 /dev/md3 flexible
> --set-defaults --create-device --on-io-error=detach' terminated with
> exit code 10

"interessting" :)
we should catch this in drbdsetup already...
and improve on the "error message".
and document this in some "quick start guide to drbd8",
the way I did for drbd 0.7 back then.

it does work with "internal" instead of "flexible".
to drbdsetup, "flexible" means "flexible external",
and that correctly won't work if the "external meta data device"
is the same as the "storage device".

to drbdmeta, unfortunately there is "internal" as well as "flex-internal",
which mean the same thing for drbd 8, but not for 0.7, for compatibility
reasons...

>     flexible-meta-disk  internal;

if it is internal, it does not matter whether you say "flexible" or not.

if you do "drbdadm -d attach drbd0",
it will print you the drbdsetup command it would execute.

that should say "internal" not "flexible" on the commandline.
otherwise you found a bug. works for me, though...

-- 
: Lars Ellenberg                            Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH      Fax +43-1-8178292-82 :
: Vivenotgasse 48, A-1120 Vienna/Europe    http://www.linbit.com :
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