From: NeilBrown <neilb@suse.de>
To: "Kwolek, Adam" <adam.kwolek@intel.com>
Cc: "linux-raid@vger.kernel.org" <linux-raid@vger.kernel.org>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"Ciechanowski, Ed" <ed.ciechanowski@intel.com>,
"Neubauer, Wojciech" <Wojciech.Neubauer@intel.com>
Subject: Re: [PATCH 6/9] imsm: FIX: container content gathering is not needed for size set
Date: Thu, 13 Jan 2011 14:04:38 +1100 [thread overview]
Message-ID: <20110113140438.6f62ef2b@notabene.brown> (raw)
In-Reply-To: <905EDD02F158D948B186911EB64DB3D176E1AD80@irsmsx503.ger.corp.intel.com>
On Wed, 12 Jan 2011 15:30:50 +0000 "Kwolek, Adam" <adam.kwolek@intel.com>
wrote:
>
>
> > -----Original Message-----
> > From: NeilBrown [mailto:neilb@suse.de]
> > Sent: Wednesday, January 12, 2011 6:53 AM
> > To: Kwolek, Adam
> > Cc: linux-raid@vger.kernel.org; Williams, Dan J; Ciechanowski, Ed;
> > Neubauer, Wojciech
> > Subject: Re: [PATCH 6/9] imsm: FIX: container content gathering is not
> > needed for size set
> >
> > On Tue, 11 Jan 2011 15:04:35 +0100 Adam Kwolek <adam.kwolek@intel.com>
> > wrote:
> >
> > > Size information is loaded already and there is no need to load it
> > again,
> > > when metadata is not reloaded.
> >
> > Why do you say that? It seems wrong.
> >
> > When growing an array, the size will not change until the reshape
> > completes.
> > When it does complete, it will be mdmon which updates the metadata and
> > records in it the desired size of the array.
> >
> > The only way mdadm can find this number out is by loading the metadata.
> >
> > Where am I wrong?
> >
> > NeilBrown
>
> Size is set in metadata, before reshape start in reshape_super() and remains unchanged during whole reshape.
> After reshape this value doesn't change in metadata also.
> It is possible that this behavior is imsm specific, and for general case reload is required as you describes.
>
If reshape_super does to that (and it looks like it does) then I strongly
suspect that it is wrong.
While an array is in the middle of a migration from one configuration to
another its effective size must be the smaller of those two sizes.
So when we add a device to a RAID5, the device size must stay unchanged until
the migration completes. At the moment when the migration completes the size
can change, not before. So I suspect that the size recorded in the metadata
should be the smaller size.
So I think that apply_reshape_container_disks_update and
imsm_progress_container_reshape need to be fixed to change the size after the migration.
NeilBrown
next prev parent reply other threads:[~2011-01-13 3:04 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-11 14:03 [PATCH 0/9] OLCE for external meta (cont.) Adam Kwolek
2011-01-11 14:03 ` [PATCH 1/9] imsm: FIX: set correct slot information in metadata (raid0) Adam Kwolek
2011-01-11 14:04 ` [PATCH 2/9] FIX: Cannot add spare to monitored container Adam Kwolek
2011-01-12 5:43 ` NeilBrown
2011-01-12 15:57 ` Kwolek, Adam
2011-01-13 3:07 ` NeilBrown
2011-01-13 15:15 ` Czarnowska, Anna
2011-01-11 14:04 ` [PATCH 3/9] imsm:FIX: one spare can be added to raid0 only Adam Kwolek
2011-01-12 5:44 ` NeilBrown
2011-01-12 15:15 ` Kwolek, Adam
2011-01-11 14:04 ` [PATCH 4/9] imsm: FIX: only one spare is passed in update Adam Kwolek
2011-01-12 5:46 ` NeilBrown
2011-01-11 14:04 ` [PATCH 5/9] imsm: Update metadata for second array Adam Kwolek
2011-01-12 5:48 ` NeilBrown
2011-01-11 14:04 ` [PATCH 6/9] imsm: FIX: container content gathering is not needed for size set Adam Kwolek
2011-01-12 5:52 ` NeilBrown
2011-01-12 15:30 ` Kwolek, Adam
2011-01-13 3:04 ` NeilBrown [this message]
2011-01-11 14:04 ` [PATCH 7/9] imsm: FIX: monitor should initialize 2nd reshape only Adam Kwolek
2011-01-12 5:57 ` NeilBrown
2011-01-11 14:04 ` [PATCH 8/9] FIX: container has to be frozen during reshape Adam Kwolek
2011-01-11 14:04 ` [PATCH 9/9] imsm: Proceed with second array reshape only for frozen container Adam Kwolek
2011-01-11 15:23 ` [PATCH 0/4] RAID 0 to/from RAID5 migration Labun, Marcin
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