Hello Theodore, > On 21 Nov 2018, at 03:07, Theodore Y. Ts'o <tytso@xxxxxxx> wrote: > > *) Drop support for nodelalloc, and make delayed allocation the > default. (This requires dropping data=journal mode, since > data=journal mode does not co-exist with delalloc.) > > The last was assuming that there really wasn't good use cases where > people would really want to use nodelalloc, aside from ext3 > bug-for-bug compatibility, and hopefully since most people are using > ext4 these days, it becomes easier to make the case tha we don't need > to support ext3's unusual performance attributes. Currently Lustre FS uses “nodelalloc” option at least because of this two reasons: - OSD (layer that interact with EXT4 (LDISKFS backend) expect synchronous behaviour. - delalloc optimise block allocation the way useless for Lustre FS, because data is striped across of OSTs. Lustre FS has its own optimisations. Its behaviour similar with data=journal journaling mode. “Journal” is stored on clients and OST recovery is like journal replay. Best regards, Artem Blagodarenko.
