Hi Sage Weil <sage@xxxxxxxxxxx> writes: > Dan at CERN noticed that his performance was tanking because updatedb was > running against /var/lib/ceph. updatedb has a PRUNE line in > /etc/updatedb.conf that we should presumably be adding ourselves to. One > user pointed out a package that uses sed to rewrite this line in the init > script on start. > > I have two questions: > > - is there no better way than sed to add ourselves to this list? > - should we do it in the init script, or postinst, or both? > > Presumably this is a problem others have solved with other packages. At least for Debian neither solution is appropriate. Changing other packages conffiles in postinst scripts is forbidden by policy. There is also no way to preserve this reliably over upgrades without user interaction. I'm not sure if there is an explicit policy for init scripts, but this seems equally wrong. Also it's unclear how one would handle the case were an administrator does NOT want to exclude this directory. The only solution I see if you really want to completely exclude the directory is to convince the mlocate maintainers to either add the directory to the default configuration or to add something like an /etc/updatedb.d directory where packages can drop configuration file snippets. But the latter seems like overkill to me. The real question to me is why an updatedb run can drastically impact ceph performance. At least in Debian updatedb is run with ionice -c3 in the "Idle" scheduling class. According to the man page this means: "A program running with idle I/O priority will only get disk time when no other program has asked for disk I/O for a defined grace period. The impact of an idle I/O process on normal system activity should be zero. This scheduling class does not take a priority argument. Presently, this scheduling class is permitted for an ordinary user (since kernel 2.6.25)." So it should not have any negative effect. Maybe CERN (or the distribution they use) should also run updatedb under ionice. Gaudenz -- Ever tried. Ever failed. No matter. Try again. Fail again. Fail better. ~ Samuel Beckett ~ -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
