followup storage question
William A. Mahaffey III
wam at hiwaay.net
Sun Sep 13 21:43:04 UTC 2015
On 09/11/15 10:33, Graham Allan wrote:
> On 9/11/2015 7:59 AM, William A. Mahaffey III wrote:
>>
>>
>> The Wiki page https://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/9.0-RELEASE
>> illustrates using gnop to enforce 4K alignment of gpt partitions for
>> subsequent use by ZFS. However the gpart commands also use the '-a 4k'
>> arguments, aligning partitions on 4k boundaries as I understand things.
>> Is the gnop command also necessary ? TIA & have a nice weekend.
>
> My experience is I only ever install on smaller devices so never
> really worry about 4k alignment at that time, only for making large
> storage pools later. With that mind mind here is my "easy" answer for
> 9.3 and 10.x. The installer "auto ZFS" has a 4k alignment option which
> I would assume works as advertised (having said that it would be
> simple to do a basic install and then examine that to confirm). For
> making subsequent pools, I simply set vfs.zfs.min_auto_ashift=12 is
> /etc/sysctl.conf, after which you will get 4k block alignment without
> messing with gnop. On 9.1 you had to do the gnop tricks but 9.3
> supports the auto_ashift sysctl.
>
> On 9.3+, "zpool status" also *tells you* if you got the block
> alignment wrong, which is a big help over 9.1 where it could lurk
> undetected!
>
> G.
*Eeeeeeeeek* !!!!!
[root at kabini1, /etc, 4:47:06pm] 332 % sysctl -A | grep ashift
[root at kabini1, /etc, 4:47:10pm] 333 % uname -a
FreeBSD kabini1.local 9.3-RELEASE-p24 FreeBSD 9.3-RELEASE-p24 #0: Sat
Aug 22 01:54:44 UTC 2015
root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64
[root at kabini1, /etc, 4:47:15pm] 334 %
I don't see that sysctl setting, am I missing something (No ZFS
installed on this box, BTW) ? Thanks & TIA & have a nice weekend.
--
William A. Mahaffey III
----------------------------------------------------------------------
"The M1 Garand is without doubt the finest implement of war
ever devised by man."
-- Gen. George S. Patton Jr.
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