[lustre-discuss] mdt mounting error

Brian Andrus toomuchit at gmail.com
Wed Nov 1 19:21:52 PDT 2017


There is no specific requirement in Lustre to create multiple MGS; one 
MGS will often suffice for many file systems in a subnet.

You should have one MGT, it can be mounted on more than one MGS (but 
only one at a time). You need something in place that prevents it being 
mounted more than once. ZFS has that ability.

File:Metadata Server HA Cluster Simple lowres v1.png

Brian Andrus

On 11/1/2017 7:08 PM, Parag Khuraswar wrote:
>
> I have two mds nodes. For HA purpose I mentioned –service node options
>
> mkfs.lustre --servicenode=10.2.1.204 at o2ib 
> --servicenode=10.2.1.205 at o2ib --mgs /dev/mapper/mpathc
>
> Do I have to mention mgt in command ?
>
> How many mgt’s we can have on one mds or mgs servers ?
>
> Regards,
>
> Parag
>
> *From:*lustre-discuss [mailto:lustre-discuss-bounces at lists.lustre.org] 
> *On Behalf Of *Brian Andrus
> *Sent:* Thursday, November , 2017 7:30 AM
> *To:* lustre-discuss at lists.lustre.org
> *Subject:* Re: [lustre-discuss] mdt mounting error
>
> I don't think you use the --servicenode option when formatting an 
> mgs-only disk, or the --fsname option. Neither of those apply for an 
> mgs-only with multiple filesystems.
>
> My command for a zfs backed mgs was:
>
> */mkfs.lustre --mgs --backfstype=zfs MGT/mgt/*
>
> Then I created 2 different sets of OSTs/MDTs with different fsnames, 
> but the same mgsnode.
>
> Brian Andrus
>
> On 11/1/2017 6:50 PM, Parag Khuraswar wrote:
>
>     Hi Raj,
>
>     But I have two file system. And I think one mgt can be used for
>     two filesystems. Correct me if I am wrong.
>
>     Regards,
>
>     Parag
>
>     *From:*Raj [mailto:rajgautam at gmail.com]
>     *Sent:* Wednesday, November , 2017 4:57 PM
>     *To:* Parag Khuraswar; Lustre discussion
>     *Subject:* Re: [lustre-discuss] mdt mounting error
>
>     The following can contribute to this issue:
>
>     - Missing FS name in mgt creation (it must be <=9 character
>     long): --fsname=
>
>     mkfs.lustre --servicenode=10.2.1.204 at o2ib
>     <mailto:--servicenode=10.2.1.204 at o2ib>
>     --servicenode=10.2.1.205 at o2ib
>     <mailto:--servicenode=10.2.1.205 at o2ib> *--fsname=home* --mgs
>     /dev/mapper/mpathc
>
>     - verify if /mdt directory exists
>
>     On Wed, Nov 1, 2017 at 6:16 AM Raj <rajgautam at gmail.com
>     <mailto:rajgautam at gmail.com>> wrote:
>
>         What options in mkfs.lustre did you use to format with lustre?
>
>         On Wed, Nov 1, 2017 at 6:14 AM Parag Khuraswar
>         <parag_k at citilindia.com <mailto:parag_k at citilindia.com>> wrote:
>
>             Hi Raj,
>
>             Yes, /dev/mapper/mpatha available.
>
>             I could format and mount using ext4.
>
>             Regards,
>
>             Parag
>
>             *From:*Raj [mailto:rajgautam at gmail.com
>             <mailto:rajgautam at gmail.com>]
>             *Sent:* Wednesday, November , 2017 4:39 PM
>             *To:* Parag Khuraswar; Lustre discussion
>             *Subject:* Re: [lustre-discuss] mdt mounting error
>
>             Parag,
>             Is the device /dev/mapper/mpatha available?
>             If not, the multipathd may not have started or the
>             multipath configuration may not be correct.
>
>             On Wed, Nov 1, 2017 at 5:18 AM Parag Khuraswar
>             <parag_k at citilindia.com <mailto:parag_k at citilindia.com>>
>             wrote:
>
>                 Hi,
>
>                 I am getting below error while mounting mdt. Mgt is
>                 mounted.
>
>                 Please suggest
>
>                 [root at mds2 ~]# mount -t lustre /dev/mapper/mpatha /mdt
>
>                 mount.lustre: mount /dev/mapper/mpatha at /mdt failed:
>                 No such file or directory
>
>                 Is the MGS specification correct?
>
>                 Is the filesystem name correct?
>
>                 If upgrading, is the copied client log valid? (see
>                 upgrade docs)
>
>                 Regards,
>
>                 Parag
>
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>
>
>
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