[ZFS] Booting from zpool created on 4k-sector drive

[ambrosehuang ambrose]

Here is my trick:
       1 Download the ZFS V28 patch for 8-stable,
       2 patch the 8-stable ,
       3 make buildkernel,
       4 then you will get gptzfsboot, zfsloader, pmbr
       5 install pmbr according to wiki/GPTboot
       6 replace your old gptzfsboot, zfsloader with new ones;
       then you can work around this. It works for me( 3 WD10ears +
ZFS V15 + 8-stable)

2011/5/1 Alexander Leidinger <Alexander at leidinger.net>:
> On Tue, 21 Dec 2010 15:29:01 +0100 "Emil Smolenski" <am at raisa.eu.org>
> wrote:
>
>> Hello,
>>
>> There is a hack to force zpool creation with minimum sector size
>> equal to 4k:
>>
>> # gnop create -S 4096 ${DEV0}
>> # zpool create tank ${DEV0}.nop
>> # zpool export tank
>> # gnop destroy ${DEV0}.nop
>> # zpool import tank
>>
>> Zpool created this way is much faster on problematic 4k sector
>> drives which lies about its sector size (like WD EARS). This hack
>> works perfectly fine when system is running. Gnop layer is created
>> only for "zpool create" command -- ZFS stores information about
>> sector size in its metadata. After zpool creation one can export the
>> pool, remove gnop layer and reimport the pool. Difference can be seen
>> in the output from the zdb command:
>>
>> - on 512 sector device (2**9 = 512):
>> % zdb tank |grep ashift
>> ashift=9
>>
>> - on 4096 sector device (2**12 = 4096):
>> % zdb tank |grep ashift
>> ashift=12
>>
>> This change is permanent. The only possibility to change the value
>> of ashift is: zpool destroy/create and restoring pool from backup.
>>
>> But there is one problem: I cannot boot from such pool. Error message:
>>
>> ZFS: i/o error - all block copies unavailable
>> ZFS: can't read MOS
>> ZFS: unexpected object set type 0
>
> FYI: I can boot successfully from a ZFS v28 pool which was created like
> this in a GPT partition (tested with 9-current).
>
> Bye,
> Alexander.
>
> --
> http://www.Leidinger.net    Alexander @ Leidinger.net: PGP ID = B0063FE7
> http://www.FreeBSD.org       netchild @ FreeBSD.org  : PGP ID = 72077137
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