[DRBD-user] Increasing a DRBD array

Andreas Kurz andreas at hastexo.com
Fri Oct 21 23:26:13 CEST 2011

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On 10/21/2011 10:48 PM, Gerald Brandt wrote:
> Hi,
> 
> DRBD is running directly on md0.  /dev/drbd1 is then exported via iSCSI.
> 
> The logs show:
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.332010] drbd: initialized.
> Version: 8.3.7 (api:88/proto:86-91)
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.332012] drbd: GIT-hash:
> ea9e28dbff98e331a62bcbcc63a6135808fe2917 build by root at filer-1,
> 2011-03-05 08:29:38
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.332014] drbd: registered as
> block device major 147
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.332015] drbd: minor_table @
> 0xffff88021dbaf300
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.334144] block drbd1:
> Starting worker thread (from cqueue [1489])
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.334177] block drbd1: ==>
> truncating very big lower level device to currently maximum possible
> 8587575296 sectors <==
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.334179] block drbd1: ==>>
> using internal or flexible meta data may help <<==
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.334188] block drbd1: disk(
> Diskless -> Attaching )
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.353306] Loading iSCSI
> transport class v2.0-870.
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.360582] skge eth0:
> disabling interface
> Oct 21 15:34:53 iscsi-filer-1 iscsid: iSCSI logger with pid=1515 started!
> Oct 21 15:34:53 iscsi-filer-1 kernel: [    7.381956] iscsi: registered
> transport (iser)
> Oct 21 15:34:53 iscsi-filer-1 init: ssh main process (1162) terminated
> with status 255
> Oct 21 15:34:53 iscsi-filer-1 postfix/master[1411]: reload -- version
> 2.7.0, configuration /etc/postfix
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.584678] block drbd1: Found
> 57 transactions (3507 active extents) in activity log.  
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.584684] block drbd1: Method
> to ensure write ordering: barrier
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.584691] block drbd1:
> Backing device's merge_bvec_fn() = ffffffffa00c0100
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.584694] block drbd1:
> max_segment_size ( = BIO size ) = 4096
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.584698] block drbd1:
> Adjusting my ra_pages to backing device's (32 -> 96)
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.584704] block drbd1:
> drbd_bm_resize called with capacity == 8587575296
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.603470] block drbd1: resync
> bitmap: bits=1073446912 words=16772608
> Oct 21 15:34:54 iscsi-filer-1 kernel: [    7.603474] block drbd1: size =
> 4095 GB (4293787648 KB)
> 
> The lines in yellow bug me.  I don't recall see them before.
> 
> I had a 4 disk RAID-6 md0 (4x2TB = 4 TB RAID-6).  I added a single drive
> (5x2TB = 6 TB array).

Not using "meta-disk internal" or "flexible-meta-disk" limits the device
size to 4TB (=128MB meta data size) ... change your metadata config ...
as the logs suggest ... if you want to use all 6TB

Regards,
Andreas

-- 
Need help with DRBD?
http://www.hastexo.com/now

> 
> Any ideas?
> 
> Gerald
> 
> 
> ------------------------------------------------------------------------
> 
>     From: "Andreas Kurz" <andreas at hastexo.com>
>      To: drbd-user at lists.linbit.com
>      Sent: Friday, October 21, 2011 2:55:06 PM
>      Subject: Re: [DRBD-user] Increasing a DRBD array
>      
>      On 10/21/2011 09:30 PM, Gerald Brandt wrote:
>      > Hi,
>      >
>      > I've successfully resize the lower level RAID-6 array, and grown
>      > it.  I'm now attempting to resize drbd, and nothing seems to
>      > happen.
>      >
>      > /dev/md0 is definitely bigger.
>      >
>      > What should I see during a drbd resize?
>      
>      You should see a DRBD resync of the newly added space.
>      
>      What is the lower level device of your DRBD resource? The whole md0,
>      a
>      partition on md0, a lv on a vg on a pv on md0?
>      
>      ... so if the lower level device has been resized on both nodes, DRBD
>      should definitely grow on a "drbdadm resize".
>      
>      Did I mention that on starting DRBD it is resized automatically if a
>      bigger lower level device is detected? ... have a look at the kernel
>      logs...
>      
>      Regards,
>      Andreas
>      
>      --
>      Need help with DRBD?
>      http://www.hastexo.com/now
>      
>      >
>      > Gerald
>      >
>      >
>      > ----- Original Message -----
>      >> From: "Gerald Brandt" <gbr at majentis.com>
>      >> To: drbd-user at lists.linbit.com
>      >> Sent: Tuesday, October 18, 2011 7:08:55 AM
>      >> Subject: Re: [DRBD-user] Increasing a DRBD array
>      >>
>      >> Hi,
>      >>
>      >> Okay, this is my list of what to do, and in what order:
>      >>
>      >> 1. remove the primary from DRBD
>      >> 2. add the physical disk to the primary
>      >> 3. add the primary back to DRBD and allow resync.
>      >> 4. remove the secondary from DRBD
>      >> 5. add the physical disk to the secondary
>      >> 6. add the secondary back to DRBD and allow resync.
>      >> 7. fdisk and add the disk to the RAID array on primary and
>      >> secondary
>      >> 8. grow the RAID array on the primary and secondary (while mounted
>      >> or
>      >> not mounted?)
>      >> 9. drbdadm resize on the primary (can this be done while drbd is
>      >> in
>      >> use?)
>      >> 10. expand the file system on the primary only (via Citrix
>      >> XenServer
>      >> (iSCSI))
>      >>
>      >> That sounds about right.  As long as I don't lose data. (yeah,
>      >> backups.  That's left up to my client, but becomes my problem if
>      >> they failed.)
>      >>
>      >> Gerald
>      >>
>      >>
>      >>
>      >> ----- Original Message -----
>      >>> From: "Florian Haas" <florian at hastexo.com>
>      >>> To: drbd-user at lists.linbit.com
>      >>> Sent: Tuesday, October 18, 2011 3:53:11 AM
>      >>> Subject: Re: [DRBD-user] Increasing a DRBD array
>      >>>
>      >>> On 2011-10-17 22:19, Matt Graham wrote:
>      >>>>>> Your DRBD uses the MD RAID as its backing device, doesn't it?
>      >>>>>> That means you'll have add the drive and resize your RAID
>      >>>>>> first,
>      >>>>>> then
>      >>>>>> you can resize your DRBD, and then expand the file system.
>      >>>>> Definitely built on top of the RAID.  I'm a bit confused by
>      >>>>> your
>      >>>>> answer though.  Step 8 grows the RAID array, and I don't have a
>      >>>>> step
>      >>>>> to grow DRBD.  Does that mean I'm missing something?
>      >>>>
>      >>>> 8. mdadm --grow /dev/md0 (other mdadm options)
>      >>>>    Do that on both machines.
>      >>>> 8.1 (on secondary) drbdsetup /dev/drbd0 resize
>      >>>> 8.2 (on primary) drbdsetup /dev/drbd0 resize
>      >>>
>      >>> There's a "resize" subcommand for drbdadm too; no need to use
>      >>> drbdsetup.
>      >>> And it needs to be done on one node only. Just do "drbdadm resize
>      >>> <resourcename>" on the primary while the two nodes are connected,
>      >>> and
>      >>> you're good to go.
>      >>>
>      >>>>    The softRAID is below the DRBD device.  Once the softRAID is
>      >>>>    larger, the DRBD device needs to be informed of this fact.
>      >>>>    When making arrays/devices larger, you go bottom-up; you make
>      >>>>    the hardware changes first, then softRAID changes, then DRBD
>      >>>>    changes, then filesystem changes.
>      >>>> 9. (on primary) resize2fs /dev/drbd0
>      >>>
>      >>> If it's ext3 and if it supports on-line resizing, of course. But
>      >>> that
>      >>> should be obvious.
>      >>>
>      >>> Cheers,
>      >>> Florian
>      >>>
>      >>> --
>      >>> Need help with DRBD?
>      >>> http://www.hastexo.com/knowledge/drbd
>      >>> _______________________________________________
>      >>> drbd-user mailing list
>      >>> drbd-user at lists.linbit.com
>      >>> http://lists.linbit.com/mailman/listinfo/drbd-user
>      >>>
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