Re: Odd ZFS boot module issue on r332158

> On 10 Apr 2018, at 15:27, Andrew Gallatin <gallatin_at_cs.duke.edu> wrote:
> 
> On 04/09/18 23:33, Allan Jude wrote:
>> On 2018-04-09 19:11, Andrew Gallatin wrote:
>>> I updated my main amd64 workstation to r332158 from something much
>>> earlier (mid Jan).
>>> 
>>> Upon reboot, all seemed well.  However, I later realized that the vmm.ko
>>> module was not loaded at boot, because bhyve PCI passthru did not
>>> work.  My loader.conf looks like (I'm passing a USB interface through):
>>> 
>>> #######
>>> vmm_load="YES"
>>> opensolaris_load="YES"
>>> zfs_load="YES"
>>> nvidia_load="YES"
>>> nvidia-modeset_load="YES"
>>> 
>>> # Tune ZFS Arc Size - Change to adjust memory used for disk cache
>>> vfs.zfs.arc_max="4096M"
>>> hint.xhci.2.disabled="1"
>>> pptdevs="8/0/0"
>>> hw.dmar.enable="0"
>>> cuse_load="YES"
>>> #######
>>> 
>>> The problem seems "random".  I rebooted into single-user to
>>> see if somehow, vmm.ko was loaded at boot and something
>>> was unloading vmm.ko.  However, on this boot it was loaded.  I then
>>> ^D'ed and continued to multi-user, where X failed to start because
>>> this time, the nvidia modules were not loaded.  (but nvidia had
>>> been loaded on the 1st boot).
>>> 
>>> So it *seems* like different modules are randomly not loaded by the
>>> loader, at boot.   The ZFS config is:
>>> 
>>> config:
>>> 
>>>         NAME        STATE     READ WRITE CKSUM
>>>         tank        ONLINE       0     0     0
>>>           mirror-0  ONLINE       0     0     0
>>>             ada0p2  ONLINE       0     0     0
>>>             da3p2   ONLINE       0     0     0
>>>           mirror-1  ONLINE       0     0     0
>>>             ada1p2  ONLINE       0     0     0
>>>             da0p2   ONLINE       0     0     0
>>>         cache
>>>           da2s1d    ONLINE       0     0     0
>>> 
>>> The data drives in the pool are all exactly like this:
>>> 
>>> =>        34  9767541101  ada0  GPT  (4.5T)
>>>           34           6        - free -  (3.0K)
>>>           40      204800     1  efi  (100M)
>>>       204840  9763209216     2  freebsd-zfs  (4.5T)
>>>   9763414056     4096000     3  freebsd-swap  (2.0G)
>>>   9767510056       31079        - free -  (15M)
>>> 
>>> 
>>> There is about 1.44T used in the pool.  I have no idea
>>> how ZFS mirrors work, but I'm wondering if somehow this
>>> is a 2T problem, and there are issues with blocks on
>>> difference sides of the mirror being across the 2T boundary.
>>> 
>>> Sorry to be so vague.. but this is the one machine I *don't* have
>>> a serial console on, so I don't have good logs.
>>> 
>>> Drew
>>> 
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>> What makes you think it is related to ZFS?
>> Are there any error messages when the nvidia module did not load?
> 
> I think it is related to ZFS simply because I'm booting from ZFS and
> it is not working reliably.  Our systems at work, booting from UFS on
> roughly the same svn rev seem to still load modules reliably from
> the loader.  I know there has been a lot of work on the loader
> recently, and in a UEFE + UFS context, I've seen it fail to boot
> the right partition, etc.  However, I've never seen it fail to load
> just some modules.  The one difference between what I run at home
> and what we run at work is ZFS vs UFS.
> 
> Given that it is a glass console, I have no confidence in my ability
> to log error messages.   However, I could have sworn that I saw
> something like "io error" when it failed to load vmm.ko
> (I actually rebooted several times when I was diagnosing it..
> at first I thought xhci was holding on to the pass-thru device)
> 
> I vaguely remembered reading something about this recently.
> I just tracked it down to the "ZFS i/o error in recent 12.0"
> thread from last month, and this message in particular:
> 
> https://lists.freebsd.org/pipermail/freebsd-current/2018-March/068890.html
> 
> I'm booting via UEFI into a ZFS system with a FS that
> extends across 2TB..
> 
> Is there something like tools/diag/prtblknos for ZFS?
> 

run zpool scrub first, however, if you were able to load that module manually from OS, there is no reason to suspect the zfs corruption.

But if you really are getting IO errors, I would actually suspect that the firmware is is buggy and can not really read past 2TB, so the obvious second suggestion is to check for firmware update. The ZFS reader code does try all block copies before giving up on the block, so the third option you can test is:

1. reboot
2. press esc when the boot menu is up to get to OK prompt
3. enter:  start

this would load the configured files and you will get the error messages. Also once you have kernel loaded, you can try to load modules manually with load command.

If still nothing, the only way to ensure your data is below 2TB line is to create separate partition for boot pool or use smaller disks for OS.

rgds,
toomas