OpenSolaris

flag day: ZFS on-disk format change

Date: Fri, 3 Mar 2006 15:43:50 -0800
From: Matthew Ahrens <ahrens at sun dot com>
To: on-all at sun dot com, onnv-gate at onnv dot sfbay dot sun dot com, zfs-discuss@opensolaris.org
Subject: flag day: ZFS on-disk format change

Summary: If you use ZFS, do not downgrade from build 35 or later to
build 34 or earlier.

This putback (into Solaris Nevada build 35) introduced a backwards-
compatable change to the ZFS on-disk format.  Old pools will be
seamlessly accessed by the new code; you do not need to do anything
special.

However, do *not* downgrade from build 35 or later to build 34 or
earlier.  If you do so, some of your data may be inaccessible with the
old code, and attemts to access this data will result in an assertion
failure in zap.c.

We have fixed the version-checking code so that if a similar change
needs to be made in the future, the old code will fail gracefully with
an informative error message.

Thanks,
~--matt

ps. Sorry for the late notice.

On Sat, Feb 25, 2006 at 07:16:58PM -0800, Matthew Ahrens wrote:
> Event:            putback-to
> Parent workspace: /ws/onnv-gate
>                   (elpaso:/ws/onnv-gate)
> Child workspace:  /home/ahrens/zapbs
>                   (zion.eng:/export/home/ahrens/zapbs)
> User:             ahrens
>> Comment:
> 6389368 fat zap should use 16k blocks (with backwards compatability)
>> Files:
> update: usr/src/uts/common/fs/zfs/dbuf.c
> update: usr/src/uts/common/fs/zfs/dmu_tx.c
> update: usr/src/uts/common/fs/zfs/dnode.c
> update: usr/src/uts/common/fs/zfs/sys/zap_impl.h
> update: usr/src/uts/common/fs/zfs/sys/zap_leaf.h
> update: usr/src/uts/common/fs/zfs/zap.c
> update: usr/src/uts/common/fs/zfs/zap_leaf.c
> update: usr/src/uts/common/fs/zfs/zap_micro.c
>> Examined files: 8
>> Contents Summary:
>        8   update

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