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

Simon Carey-Smith clipclopnz at gmail.com
Thu Jun 5 08:09:12 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.

>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;

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 
    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 
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.

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