[DRBD-user] Does syncing affect File Descriptor access on applications running on the DRBD device?

Gabriel Wong grwong_gt at yahoo.com
Wed Oct 28 19:22:07 CET 2009

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

Hope I did not double post - Apologies if I did.
I am using DRBD 8.2.6.
The application is qmail in a Centos 4.8 openVZ VPS. The VPS runs on the DRBD device.

While syncing, no mail gets delivered (to local or remote destinations), although they appear in the qmail queue.

If I disconnect the primary node, mail is delivered.

Reading qmail documentation, qmail forks the messages in the queue to qmail-send, which hands off to
either qmail-lspawn (local) or qmail-rspawn (remote) for mail processing.

From the qmail docs:
    qmail-lspawn reads a series of local delivery commands  from
    descriptor 0, invokes qmail-local to perform the deliveries,
    and  prints  the  results  to  descriptor  1.    It  passes
    aliasempty  to  qmail-local as the default delivery instruc-

This leads to the question, is there some sort of block on the fd (or other related IO services) while DRBD is syncing?

Thanks in advance.

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