> > Here are 4 questions which we cannot find answers in LU-1586: > 1. According to Andres?s reply, there should some unconsumed > changelog files on our MDT, and these files have taken all the space (file > quotas?) Lustre gives to changelog. With Lustre 2.1, these files are under > OBJECTS directory and can be listed in ldiskfs mode. In our case, with > Lustre 2.5.3, there is no OBJECTS directory can be found. In this case, how > can we monitor the situation before the unconsumed changelogs takes up all > the disk space? > The changelog base on one catalog file and a plain llog files. Catalog stores limited number of records about 64768. A catalog record size is 64 byte. Each record has information about plain llog file. A plain llog file stores records about IO operation. A number of records at the plain llog file is about 64768 with different record size. So changelog could store 64768^2 IO operations and it occupy filesystem space. The error "no free catalog slots" is happened when changelog catalog doesn`t have a slot to store a record about new plain lllog. All slots are filled or internal changelog markers became crazy and internal logic don`t work. To be closer to the root cause, you need to dump a changelog catalog and check bitmap. Is there free slots? Something like
debugfs -R "dump changelog_catalog changelog_catalog.dmp" /dev/md55 && used=`llog_reader changelog_catalog.dmp | grep "type=1064553b" | wc -l` 2. Why there are so many unconsumed changelogs? Could it related to > our frequent remount of MDT( abort_recovery mode )? > umount operation create half empty plain llog file. And changelog_clear can`t remove it, if all slots is freed. Only new mount can remove that file. It could be related or not. > 3. When we remount the MDT, robinhood is still running. Why robinhood > can not consume those old changelogs after MDT service is recovered? > 4. Why there is a huge difference between current index(4199610352 ) and > cl1(49035933) index? > > Thank you for your time and help ! > > Wang,Lu > -- Alexander Boyko Seagate www.seagate.com
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