[LU-10760] MGS startup is happening asynchronously and taking a long time

• Type: Bug
• Resolution: Not a Bug
• Priority: Critical
• Affects Version/s: Lustre 2.10.4
• Severity: 3
• Assignee: Nathaniel Clark
• Reporter: Brian Murrell (Inactive)

Description

I have noticed that from 2.10.3 to b2_10 MGS startup is happening asynchronously and taking much longer.

In 2.10.3, immediately after (or within a very small number of seconds at most) the mount for the MGS returns it reports as being up:

# mount -t lustre zfs_pool_scsi0QEMU_QEMU_HARDDISK_disk13/MGS /mnt/MGS
# lctl dl:
  0 UP osd-zfs MGS-osd MGS-osd_UUID 4
  1 UP mgs MGS MGS 4
  2 UP mgc MGC10.14.83.84@tcp f2845b74-6eb5-07a5-1aaa-d7c54f76df5f 4

However the same operation on b2_10 is taking on the order of 10-11 seconds after the mount returns before lctl dl shows the MGS as being up.

I have attached debug-lctl-1519949571.log.xz which is a lustre debug log of the mount an lctl conf_param where it takes 10-11 seconds before the lctl conf_param returns with success instead of a -19.