Upgrade to 9.0: How to convert zpool from adX to adaX?

[krad]

On 5 January 2012 11:55, Miroslav Lachman <000.fbsd at quip.cz> wrote:

> Martin Birgmeier wrote:
>
>> On 01/05/12 10:35, Volodymyr Kostyrko wrote:
>>
>>> 05.01.2012 09:59, Martin Birgmeier wrote:
>>>
>>>> In 9.0, if I keep kern.cam.ada.legacy_aliases=1, there will be two paths
>>>> to each device, one through adX, the other through adaX. Which one will
>>>> zfs use, and show with 'zpool status'?
>>>>
>>>
>>> You are partially incorrect here:
>>> [torn] ~> ls -la /dev | grep ad
>>> lrwxr-xr-x 1 root wheel 4 5 jan 08:22 ad6@ -> ada0
>>> lrwxr-xr-x 1 root wheel 5 5 jan 08:22 ad6a@ -> ada0a
>>> lrwxr-xr-x 1 root wheel 5 5 jan 08:22 ad6b@ -> ada0b
>>> lrwxr-xr-x 1 root wheel 5 5 jan 08:22 ad6d@ -> ada0d
>>> lrwxr-xr-x 1 root wheel 5 5 jan 08:22 ad6e@ -> ada0e
>>> lrwxr-xr-x 1 root wheel 5 5 jan 08:22 ad6f@ -> ada0f
>>> lrwxr-xr-x 1 root wheel 13 5 jan 08:22 ad6f.journal@ -> ada0f.journal
>>> crw-r----- 1 root operator 0, 64 5 jan 08:22 ada0
>>> crw-r----- 1 root operator 0, 66 5 jan 08:23 ada0a
>>> crw-r----- 1 root operator 0, 68 5 jan 08:22 ada0b
>>> crw-r----- 1 root operator 0, 70 5 jan 08:23 ada0d
>>> crw-r----- 1 root operator 0, 72 5 jan 08:23 ada0e
>>> crw-r----- 1 root operator 0, 74 5 jan 08:22 ada0f
>>> crw-r----- 1 root operator 0, 79 5 jan 08:23 ada0f.journal
>>>
>>>  Also, I understand that I will have to wire down the various ATA CAMs to
>>>> obtain the old numbering. How can I do this? Again, which path would zfs
>>>> use if I did not wire down the ATA CAMs? Will I have half of my devices
>>>> go through adX and the other through adaX, or will zfs even believe that
>>>> it has a multipath connectivity to each device?
>>>>
>>>
>>> Not at all, ad6 would be a symlink to correct ada device, I haven't
>>> yet changed the fstab on this machine and it reads:
>>>
>>> # Device Mountpoint FStype Options Dump Pass#
>>> /dev/ad6b none swap sw 0 0
>>> /dev/ad6a / ufs rw 1 1
>>> /dev/ad6e /tmp ufs rw 2 2
>>> /dev/ad6f.journal /usr ufs rw,async 2 2
>>> /dev/ad6d /var ufs rw 2 2
>>> /dev/cd0 /cdrom cd9660 ro,noauto 0 0
>>>
>>>  Sigh... I get only half the answers, and these are not so helpful
>> either.
>>
>> First of all, I *am* correct in saying that there are two paths to the
>> same device, because the purpose of a (sym-)link precisely is to have an
>> alternate path to the same object in the filesystem. So if someone tells
>> me that zfs somehow (how?) excludes devices reached through symlinks,
>> *that* would be an information I would find useful.
>>
>> Second, the whole purpose of the kern.cam.ada.legacy_aliases is to have
>> backwards compatibility for fstab etc by installing symlinks in /dev. I
>> know this very well but want to prepare for the day when I want to get
>> rid of the necessity for this compatibility.
>>
>> Third, I have now asked twice how to wire the ATA CAM devices, without
>> anybody even referring to that question. Well, I guess I'll have to find
>> that out myself.
>>
>> I do appreciate all answers, even more so as I perfectly understand they
>> are *free* answers, and maybe the above is even helpful to someone else
>> (and does not confuse them instead), but I'd appreciate it even more if
>> they were real answers.
>>
>
> ZFS taste available devices on boot, find ondisk stored metadata and
> additionally useses informations stored in /boot/zfs/zpool.cache
>
> "ad" to "ada" transition is not the only case where one disk device is
> accessible by multiple ways.
> On one of my servers with SAS drives, the ZFS partitions can be accessed
> by /dev/daXsY or /dev/gpt/<gpt_label> or /dev/gptid/<long-uuid-string>
> It works correctly without any confusions.
>
> If you will delete zpool.cache and then export / import pool, the member
> devices will be named as "first tasted". So if you will disable symlinks to
> "ad" device names, your zpool will be correctly loaded with new device
> names. ZFS is smart enough to not depend on device names and order. You can
> safely change order of cables / devices on controller and ZFS will start
> without any problem.
> So the problem with "ad" to "ada" transition on ZFS is rather cosmetic
> (device names shown in zpool status output) but it will work with whatever
> names.
> You just need to fix UFS / fstab issues.
>
> Miroslav Lachman
>
> ______________________________**_________________
> freebsd-fs at freebsd.org mailing list
> http://lists.freebsd.org/**mailman/listinfo/freebsd-fs<http://lists.freebsd.org/mailman/listinfo/freebsd-fs>
> To unsubscribe, send any mail to "freebsd-fs-unsubscribe@**freebsd.org<freebsd-fs-unsubscribe at freebsd.org>
> "
>


and if you implement gpt or geom labeling event the ufs issues become a non
event