[lustre-discuss] [EXTERNAL] [BULK] Re: Wrong striping when creating files inside a directory with explicit layout

[Mohr, Rick]

That is correct.  The behavior can be different if you open in append mode versus just opening and then appending.  For example, if you have a directory with default stripe count of 3, then running "touch foo; echo 'a' >> foo" will create a file with stripe count 3.  But if the file is create by just running " echo 'a' >> foo", then the file will be created with stripe count 1 by default.  The default striping for O_APPEND files can be controlled with the append_stripe_count parameter.  See https://doc.lustre.org/lustre_manual.xhtml#file_striping.considerations for more details.

(Santiago: That could explain why you were getting files with stripe count 1.  I missed the info about appending to files when I first read your message.)

--Rick

On 12/8/25, 10:36 AM, "lustre-discuss on behalf of Vicker, Darby J. (JSC-EG311)[AMENTUM TECHNOLOGY, INC] via lustre-discuss" <lustre-discuss-bounces at lists.lustre.org <mailto:lustre-discuss-bounces at lists.lustre.org> on behalf of lustre-discuss at lists.lustre.org <mailto:lustre-discuss at lists.lustre.org>> wrote:

> The application creates files with standard POSIX I/O (open() followed by appends and writes), nothing exotic or MPI-IO-related.

If I remember correctly, files opened in append mode are treated differently by the lustre client and don’t necessarily obey the stripping set on its parent directory. I don’t recall the details at the moment but perhaps that is contributing to the behavior Santiago is experiencing?