[DRBD-user] Online verify (verify-alg) parameter in drbd.conf

Lars Ellenberg lars.ellenberg at linbit.com
Thu Jun 5 10:06:07 CEST 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 Thu, Jun 05, 2008 at 08:09:12AM +0200, Simon Carey-Smith wrote:
> >From the online DRBD user gude, to enable online verification according to 
> chapter 6 ('Enabling on-line verification') we need to add a line to the 
> syncer section of the resource:
>     verify-alg algorithm;     # where algorithm is supported by kernel, eg: 
> md5 / sha1 / crc32c
> Under Appendix A for drbd.conf however it says to add the line:
>     data-integrity-alg alg;

these are two different things.  don't mix them up.

Replication traffic integrity checking,
net { data-integrity-alg "crc32c"; }

On-line device verification,
syncer { verify-alg "md5"; }

> We're using drbd-8.2.5 and have tried both options but can't get either to 
> work.   Using 'data-integrity-alg' spits back an error when DRBD starts 
> saying that it found an unknown option in the conf, whereas using 
> 'verify-alg' (with md5 or sha1) gives this message in the syslog when DRBD 
> starts:
>     localhost kernel: drbd0: data-integrity-alg: <not-used>
> The user guide says that the algorithm used can be "any message digest 
> algorithm supported by the kernel crypto API in your system's kernel 
> configuration."
> Would we get this messages because the linux kernel doesn't support 
> cryptography?  We're running Fedora 8 so this would be surprising.   How to 
> find out which crypto algorithms the kernel supports?  It might be worth 
> adding a comment to the user gude about how to do this.
> Cheers 

: 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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