On 2013/10/14 12:31 PM, "Lambert, Cedric" <[email protected]> wrote: >OK, this mounting options does perfectly the trick for my performance >tests. Thanks for your help. >However, I do not understand why I fall into this problem, and maybe some >of you could help me : >I think there is something I did not understand in the mkfs options since >my MDT behaves perfectly and its formatting takes a long time. >It is not the case for my OSTs. >Here are the mkfs_cmd used for my Lustre targets : >Mkfs_cmd for my MDT : mke2fs -j -b 4096 -L scratch:MDT0000 -J size=400 >-I 512 -i 2048 -q -O >dirdata,uninit_bg,^extents,dir_nlink,quota,huge_file,flex_bg -E >lazy_journal_init -F /dev/sdb2 97177856 >Mkfs_cmd for my OSTs : mke2fs -j -b 4096 -L scratch:OST0000 -J size=400 >-I 256 -i 524288 -q -O >extents,uninit_bg,dir_nlink,quota,huge_file,flex_bg -G 256 -E >stride=64,lazy_itable_init=0,lazy_journal_init=0,resize=4290772992 -F >/dev/sdc 2441822902 > >When I format my OSTs with lazy_itable_init=0,lazy_journal_init=0 , it >takes approximatively 12 seconds for the formatting. Without these >options it is instantaneous. Thus, there is a difference in the behavior >of the command, but 12 seconds is not a lot for formatting 10 TB ! > >Do you have any idea what's wrong in my OST formatting ?
The OSTs have far fewer inodes (one inode per 1MB of space on large OSTs) compared to the MDT (one inode per 2kB). Also, the OSTs use a flex_bg factor of 256 instead of 32, so it also reduces seeking for bitmap writes by a factor 8. So it may well be that the OST formatting is actually being completed that much more quickly than the MDT formatting. Cheers, Andreas >Thank you >Cédric > > >-----Original Message----- >From: Dilger, Andreas [mailto:[email protected]] >Sent: lundi 14 octobre 2013 19:13 >To: Lambert, Cedric >Cc: [email protected] >Subject: Re: [Lustre-discuss] Ldiskfs formatting > >You can try mounting the OST with "-o noinit_itable". This doesn't fix >the formatting (not sure why that isn't being recognized), but it >prevents the kernel thread from zeroing the inode table. > >This could cause problems for e2fsck in the distant future if certain >types of corruption are hit, but does not affect testing in any way > >Cheers, Andreas > >On 2013-10-14, at 7:35, "Lambert, Cedric" ><[email protected]<mailto:[email protected]>> wrote: > >Hello, > >Sorry for this trivial question, but I did not find the solution myself : >Everyone in the ldiskfs/ext4 community is happy since the OST formatting >is quicker with the uninit_bg and lazy_itable_init features. And I >appreciate a lot this feature too ! >However, today for a particular test, When I format my OSTs, I would >like this task to be completely finished in order to be sure to have the >maximum OSTs bandwidth when I run my benchmarks. > >So, I tried the following : >--mkfsoptions="-E lazy_itable_init=0,lazy_journal_init=0" but no >success : formatting is still really quick and as soon as I mount my OST, >iostats show me the formatting activity on it. > >Is it still possible to format like in the old ext3 age ? > >Thanks for your help >Cédric >_______________________________________________ >Lustre-discuss mailing list >[email protected]<mailto:[email protected]> >http://lists.lustre.org/mailman/listinfo/lustre-discuss > Cheers, Andreas -- Andreas Dilger Lustre Software Architect Intel High Performance Data Division _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
