Many thanks, Andreas! That is exactly what I need. Wei-keng
On Dec 20, 2025, at 2:13 PM, Andreas Dilger <[email protected]> wrote: There is a function to return the number of OSTs at a specific directory (it does not need to be the mount point of the filesystem): int llapi_get_obd_count(char *dir, int *count, int is_mdt); that looks like what you want. It appears there is no man page for this, so it should be added. Cheers, Andreas On Dec 20, 2025, at 12:45, Wei-Keng Liao via lustre-discuss <[email protected]> wrote: I am trying to get the total number of available OSTs given a folder name, through calls of Luster user C APIs, but failed to do so, when a layout has no pool name. I have tried the followings. At first, call llapi_layout_get_by_fd() to obtain a folder's 'layout'. llapi_layout_pool_name_get() returns successfully, but the returned pool_name is empty. llapi_getname() returns a valid fsname. llapi_get_poolmembers() returns -22 (i.e. -EINVAL), when using the 'fsname' as the argument 'poolname.' If I appended a dot, '.', to fsname, llapi_get_poolmembers() returns successfully, but the returned value is 0 (number of members). When doing my experiments on Polaris at ALCF, I have also tried the following lfs commands at the prompt of login node. % lfs pool_list /eagle Pools from eagle: % lfs getname -n /eagle eagle % lfs osts /eagle |wc -l 161 Command 'lfs osts /eagle' shows there are 160 OSTs. On Perlmutter at NERSC, its Lustre has a pool name, and thus I was able to make the above Lustre user API calls to retrieve the total number of available OSTs. In summary, my question is how do I properly make calls to Lustre user C APIs when a layout has no pool name? Wei-keng Liao _______________________________________________ lustre-discuss mailing list [email protected] https://urldefense.com/v3/__http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org__;!!Dq0X2DkFhyF93HkjWTBQKhk!R432bn01myTefro_9rhZkiZXFEVK7s8IZ44AUVxA48SvonoylTFUJ6T-I-Vj1XEquHsfNW3NJeU6_A-gWa_piDzyGvb5m8Q$
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