On Aug 11, 2016, at 03:59, Gibbins, Faye <[email protected]> wrote:
> 
> So we have three lustre nodes ATM, say A, B and C. The MSG+OSS and two 
> additional ones which are OSS's too.
> 
> In this case we have an LVM called /dev/mapper/audiodb--1--5-audiodb_0 which 
> is one part of many ext4 file systems that make up the whole audiodb file 
> system under Lustre.
> 
> I've checked all three machines and confirmed that only host A mounts that 
> LVM, however all three can see the LVM as we are multi-pathing the fibre to 
> the backend storage.
> 
> On host A I can run "tune2fs -l /dev/mapper/audiodb--1--5-audiodb_0" just 
> fine.

That's because this command is opening the filesystem read-only and does not 
trigger the MMP check.

> But when I try to run "tune2fs -e panic /dev/mapper/audiodb--1--5-audiodb_0" 
> this happens:
> 
> Snip---
> 0 A:~# tune2fs -e panic /dev/mapper/audiodb--1--5-audiodb_0
> tune2fs 1.42.13.wc4 (28-Nov-2015)

> tune2fs: MMP: device currently active while trying to open 
> /dev/mapper/audiodb--1--5-audiodb_0
> MMP error info: last update: Thu Aug 11 10:55:48 2016
> node: A device: dm-20
> 0 A:~#
> Snip---

This is what MMP is intended to avoid - multiple tools modifying the filesystem 
at the same time.  In this case, the tune2fs command is just setting a bit in 
the superblock, so in theory it should be OK to do on a running filesystem.

However, since the kernel code does not refresh the s_mount_opt flag from disk 
after it is first read at mount (see test_opt() macro), there is no benefit to 
changing this field while the filesystem is mounted, so you may as well wait 
until the next time the filesystem is remounted.

Cheers, Andreas

> Can anyone help with this?
> 
> Yours
> Faye
> 
> PS Hostnames changed.
> 
> -----Original Message-----
> From: COUVEE, PHILIPPE [mailto:[email protected]] 
> Sent: 04 August 2016 14:56
> To: Gibbins, Faye <[email protected]>; Mohr Jr, Richard Frank (Rick 
> Mohr) <[email protected]>
> Cc: [email protected]
> Subject: RE: [lustre-discuss] tune2fs being blocked by MMP
> 
> Hi,
> If I'm not wrong, MMP stands for Multiple Mount Protection, and is activated 
> to prevent mounting a device that is already mounted on another node in an HA 
> cell.
> In your case, are you trying to issue the tunefs command on the "backup" node 
> for that device ? What if you try running tunefs on the OSS where the device 
> is currently mounted ?
> Philippe
> 
> -----Original Message-----
> From: lustre-discuss [mailto:[email protected]] On 
> Behalf Of Gibbins, Faye
> Sent: Thursday, August 04, 2016 3:40 PM
> To: Mohr Jr, Richard Frank (Rick Mohr)
> Cc: [email protected]
> Subject: Re: [lustre-discuss] tune2fs being blocked by MMP
> 
> Hi,
> 
> Yes it is mounted. But that's not always a problem. We have a test lustre 
> cluster where it's mounted and the tune2fs works fine. But it fails in 
> production.
> 
> Production have failover turned on for the OSTs. Something absent on that 
> particular test cluster.
> 
> Is it possible there's something in lustre that prohibits tune2fs working 
> only when failover is on for an OST?
> 
> Faye
> 
> -----Original Message-----
> From: Mohr Jr, Richard Frank (Rick Mohr) [mailto:[email protected]]
> Sent: 02 August 2016 17:38
> To: Gibbins, Faye <[email protected]>
> Cc: [email protected]
> Subject: Re: [lustre-discuss] tune2fs being blocked by MMP
> 
> 
>> On Aug 2, 2016, at 10:38 AM, Gibbins, Faye <[email protected]> wrote:
>> 
>> 
>> tune2fs: MMP: device currently active while trying to open 
>> /dev/mapper/scratch--1--5-scratch_3
>> 
>> MMP error info: last update: Tue Aug  2 15:34:09 2016
>> 
>> node: edi-vf-1-5.ad.cirrus.com device: dm-19
>> 
>> 0 edi-vf-1-5:~#
> 
> Is the device currently mounted?  If so, that would explain the error.
> 
> --
> Rick Mohr
> Senior HPC System Administrator
> National Institute for Computational Sciences 
> https://urldefense.proofpoint.com/v2/url?u=http-3A__www.nics.tennessee.edu&d=DQIFAg&c=O3LcjD-V2Iepl5V0N1424A&r=zYKOt5zq8DxD76qBilrgQKxtITGPmVmWHHVOs6JpkMQ&m=HHqIHO6NJdOqJbinMrvMmk8S9oklNJRSgMNfnTOJLVk&s=9Ntf1l5dP_4JpRf-8OjiWKFFzwoJ5BP7VC-uNgSLF3k&e=
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