[DRBD-user] external meta data in a file - possible?

Lars Ellenberg lars.ellenberg at linbit.com
Mon Mar 3 13:50:51 CET 2008

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Mon, Mar 03, 2008 at 01:27:09PM +0100, Tomasz Chmielewski wrote:
> Is it possible to place external meta data in a file?
> Documentation states that meta-disk has to be either internal, or should 
> point to a block-device (if external).
> However, with more DRBD devices, creating a new block device for each 
> resource is a bit of an administrative burden, and sometimes, is not 
> possible at all.
> Also, Linux software RAID can keep its bitmap either internally, or in a 
> file.
> My little experimentation a while ago showed that DRBD won't work with 
> files as meta data - but maybe something changed lately (or it's a 
> planned feature)?

will never happen.

drbd meta data transactions happen within the block io path.
if you re-enter the file-io path from within the block io path,
you will eventually deadlock.

this is a fact, not an opinion.
as such, it could not be voted uppon,
even if software was a democracy.

you cannot disagree.
you can accept it - or not.

deal with it.

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