Details
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Bug
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Resolution: Fixed
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Blocker
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Lustre 2.4.0
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3
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5565
Description
When creating a new filesystem on a VM, I ran into the following problem:
$ sudo mkfs.lustre --mgs --backfstype=zfs lustre-mds/mgs > /dev/null $ sudo mount.lustre lustre-mds/mgs /mnt/lustre/local/lustre-MGS0000 mount.lustre: lustre-mds/mgs has not been formatted with mkfs.lustre or the backend filesystem type is not supported by this tool
I tracked the issue down to here:
389 int zfs_is_lustre(char *ds, unsigned *mount_type)
390 {
391 struct lustre_disk_data tmp_ldd;
392 int ret;
393
394 if (osd_zfs_setup == 0)
395 return 0;
396
397 ret = zfs_read_ldd(ds, &tmp_ldd);
398 if ((ret == 0) && (tmp_ldd.ldd_config_ver > 0) &&
399 (strlen(tmp_ldd.ldd_fsname) > 0) &&
400 (strlen(tmp_ldd.ldd_svname) > 0)) {
401 *mount_type = tmp_ldd.ldd_mount_type;
402 return 1;
403 }
404
405 return 0;
406 }
Specifically, this line:
399 (strlen(tmp_ldd.ldd_fsname) > 0) &&
Since I did not specify the -fsname option to mkfs.lustre, mount.lustre fails to recognize the data properly. Reformatting the data set, using the -fsname option mitigates the issue.
As you can see, there is no lustre:fsname property.
$ sudo zfs get all lustre-mds/mgs | grep lustre: lustre-mds/mgs lustre:flags 100 local lustre-mds/mgs lustre:svname MGS local lustre-mds/mgs lustre:version 1 local lustre-mds/mgs lustre:index 65535 local
For starters, the error reporting is horrible in this instance. I had to crack open GDB and step through the mount.lustre executable to figure out what was failing.
And secondly, the user tools should either allow the MGS to be mounted without a "fsname" (if that's possible?), or fail the mkfs.lustre command with a useful error message if --fsname is not provided.