Thanks Carlos.
Interesting info on ZFS O_DIRECT :)

Regards,
Dawid

2014-12-31 2:03 GMT+01:00 Carlos Reategui <[email protected]>:

> Glad you got it to work.
>
> BTW DirectIO support in ZFS on Linux is on the roadmap for 0.6.4 (
> https://github.com/zfsonlinux/zfs/issues/224).  However don't know when
> that is scheduled for.
>
> On Tue, Dec 30, 2014 at 4:04 PM, Dawid Kowalski <[email protected]> wrote:
>
>>  Hi Carlos,
>>
>> Thanks for hint!
>> This one worked.
>>
>> So what worked:
>> zpool -> zfs block device fomatted as ext4 and mounted as folder
>> storage repository created with ffs driver.
>> The other drivers, meaning :
>> - file, fileSR on mounted ext4 FS,
>> - ext/lvm pointed to /dev/zd0
>> - ffs directly on ZFS.
>>
>> Failed.
>>
>> Other last resort option was to create file on ZFS, losetup and create VG
>> on it.
>>
>> FFS directly on ZFS failed most probably due to unsupported O_DIRECT flag
>> (err=22) and other failed most probably for similar reasons.
>>
>> If anyone would have some questions, feel free to email me directly at
>> [email protected]
>>
>> Based on my experience, there seem to be a lot to be fixed on xen side to
>> be really user friendly/usable.
>>
>> Based on ZFS list of features there should be direct connector from Xen
>> side.
>>
>> Regards,
>> Dawid
>>
>>
>> On 30/12/14 20:04, Carlos Reategui wrote:
>>
>> Have you tried using ext4 on a ZVOL and putting your VHDs there?
>>
>>  Scroll down to the "Ext4 on a ZVOL" section:
>> https://pthree.org/2012/12/21/zfs-administration-part-xiv-zvols/
>>
>>
>> On Tue, Dec 30, 2014 at 9:45 AM, Dawid Kowalski <[email protected]>
>> wrote:
>>
>>> Just as a form of an update. I'm stuck trying to get NFS working as no
>>> other way to use ZFS in background seems to be available for me. iSCSI
>>> share option for ZFS is not available on Linux. Should I try to enable it
>>> I'd need to add third-party daemon.
>>>
>>> I'm looking forward for your help in NFS context.
>>>
>>> In regards to nosync - I'm happy to give it a try as it's just a test
>>> system now but I'd prefer to find working solution.
>>>
>>> I've spent couple of days/evenings already fighting to get Xen working
>>> on Ubuntu with ZFS and I'm close to give up and try KVM. It's way to
>>> complicated.
>>>
>>> I'll still keep trying...
>>>
>>> Thanks,
>>> Dawid
>>>
>>>
>>>
>>> On 30/12/14 18:40, Dave Scott wrote:
>>>
>>>>  On 30 Dec 2014, at 17:24, Dawid Kowalski <[email protected]> wrote:
>>>>>
>>>>> I'll answer myself.
>>>>>
>>>>> Modifying td.c line 258 to skip O_DIRECT and recompiling doesn't help.
>>>>> For some unexplained reasons, it calls O_DIRECT flag still:
>>>>>
>>>> Hm. As an experiment you could try an LD_PRELOAD wrapper like this:
>>>>
>>>> http://www.mcgill.org.za/stuff/software/nosync
>>>>
>>>> Before using anything like this for data you care about, we need to
>>>> think it through a little to make sure it’s safe. Perhaps Linux zfs support
>>>> for iSCSI is safer? (Sorry to flip-flop on this, I’m not very familiar with
>>>> ZFS)
>>>>
>>>> Cheers,
>>>> Dave
>>>>
>>>>  strace ./td-util create vhd 2048 /path/to/file
>>>>> open("/path/to/file", O_WRONLY|O_CREAT|O_TRUNC|O_DIRECT, 0644) = -1
>>>>> EINVAL (Invalid argument)
>>>>> exit_group(22)                          = ?
>>>>> +++ exited with 22 +++
>>>>>
>>>>> Checking other files with O_WRONLY flag doesn't bring any ideas as
>>>>> none of them use "O_DIRECT".
>>>>>
>>>>> lock.c:        fd = open(buf, O_WRONLY | O_CREAT, 0644);
>>>>> lock.c:        fd = open(lockfn, O_WRONLY | O_CREAT | O_EXCL, 0644);
>>>>> lock.c:                fd = open(lockfn_flink, O_WRONLY | O_CREAT,
>>>>> 0644);
>>>>> tapdisk-vbd.c:    fd = open(fn, O_WRONLY | O_CREAT | O_NONBLOCK, 0666);
>>>>> td.c:    fd = open(name, O_WRONLY | O_CREAT | O_TRUNC, 0644);
>>>>>
>>>>>
>>>>> Any ideas how to fix FileSR for ZFS on Linux?
>>>>>
>>>>> Seems like I'm left with iScsi approach only.
>>>>>
>>>>> Thanks,
>>>>> Dawid
>>>>>
>>>>> On 30/12/14 18:11, Dawid Kowalski wrote:
>>>>>
>>>>>> Hi Guys,
>>>>>>
>>>>>> Just wanted to report that file based Storage Repository won't work
>>>>>> on Linux systems as td-util is required O_DIRECT when creating image file
>>>>>> not supported on ZFS (Linux).
>>>>>>
>>>>>> When creating vm, i.e. vm-import it calls td-util similar to below:
>>>>>> td-util create vhd 2048 /path/to/file
>>>>>>
>>>>>> Strace shows:
>>>>>> open("/path/to/file", O_WRONLY|O_CREAT|O_TRUNC|O_DIRECT, 0644) = -1
>>>>>> EINVAL (Invalid argument)
>>>>>>
>>>>>> I'll try to patch td.c to skip O_DIRECT flag but this is rather dirty
>>>>>> hack than proper solution of the problem.
>>>>>>
>>>>>> Regards,
>>>>>> Dawid
>>>>>>
>>>>>
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