[DRBD-user] drbd network block device deadlock ?

Ivan Frain ivan.frain at euranova.eu
Tue Feb 1 17:52:48 CET 2011

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

Hi Antonio,

I think this problem can also happen for non-OS disks. Considering
that we access a non-OS disk , we can have pages in memory that belong
to this disk. In that case, the system may ask to flush these "dirty"
pages to the non-OS disk. And here we are: potential deadlock as I
explain in my first post.
I hope this clarify the problem.

Correct me if I have made wrong assumptions, I just want to have the
conviction that this cannot happen in production.


At Tuesday, 01/02/2011 on 17:44 Antonio Anselmi wrote:

OS disk is usually a local device and not managed by drbd, i.e. is
a backing device.
Unless I'm missing something about your question.


Lo scopo del lavoro è quello di guadagnarsi il tempo libero
The purpose of the job is to gain leisure  (Aristotele)

2011/2/1 Ivan Frain :
> Hi all,
> I am currently evaluating DRBD as a storage candidate for highly
> storage in a virtualized environment.
> It seems like a very good alternative to expensive SAN/NAS.
> I was wondering how DRBD deals with the network block device
> problem.
> This problem (described here: http://lwn.net/Articles/195416/) can
> summarized as follows: if the system runs short in memory, it will
try to
> write dirty page to disk in order to free memory space.  if the
disk is a
> network block device, the dirty page write may need to allocate
some other
> memory pages which is not possible since the solution to have more
> available was to write the dirty page to disk.
> If someone has some information about that problem I'am eager to
read it.
> Thank you in advance.
> BR,
> Ivan
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user
drbd-user mailing list
drbd-user at lists.linbit.com

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20110201/a6b824d8/attachment.htm>

More information about the drbd-user mailing list