[DRBD-user] incompatible setting of the data-integrity-alg

[Lonni J Friedman]

Hi,
I'm trying to setup a new resource on two Fedora16-x86_64 systems,
using drbd-8.3.11.  Everything seemed to be working ok, but when I set
data-integrity-alg to md5, and adjusted the resource, the primary fell
into "DUnknown".  In dmesg, I see:
incompatible setting of the data-integrity-alg

Here's my r0.res:
#########
resource r0 {
        device    /dev/drbd0;
        disk      /dev/sdb1;
        meta-disk internal;
        net {
                data-integrity-alg md5;
        }
        syncer {
                rate 30M;
                verify-alg sha1;
                csums-alg md5;
        }
        on farm-ljf0 {
                address   10.31.99.165:7789;
        }
        on farm-ljf1 {
                address   10.31.99.166:7789;
        }
}
#########

I'm guessing that for some reason md5 is not allowed for
data-integrity-alg, but I don't understand why.

Here's the current state of things:
$ cat /proc/drbd
version: 8.3.11 (api:88/proto:86-96)
srcversion: EBD919353D1D1CCDD0DFBD3
 0: cs:WFConnection ro:Primary/Unknown ds:UpToDate/DUnknown C r-----
    ns:0 nr:0 dw:524687 dr:41941337 al:135 bm:1280 lo:0 pe:0 ua:0 ap:0
ep:1 wo:f oos:0

After some digging, it looks like the secondary/peer fell into a
StandAlone state, which I fixed by doing a "drbdadm connect r0" on the
secondary.  I'm still rather confused how all of this happened, and
would appreciate some input.

Is there some safe way to determine what the "compatible" values for
data-integrity-alg are without seemingly breaking replication?

thanks