[linux-lvm] Lvm think provisioning query

[Bhasker C V]

Does this mean the ext4 is showing wrong information. The file is reported
being 90+MB but in actuality the size is less in the FS ?
This is quite ok because it is just that file system being affected. I was
however concerned that the file in this FS might have overwritten other LV
data since the file is showing bigger than the volume size.

I will try this using BTRFS.


On Fri, Apr 29, 2016 at 10:13 AM, Zdenek Kabelac <zkabelac at redhat.com>
wrote:

> On 28.4.2016 16:36, Bhasker C V wrote:
>
>> Zdenek,
>>   Thanks. Here I am just filling it up with random data and so I am not
>> concerned about data integrity
>>   You are right, I did get page lost during write errors in the kernel
>>
>> The question however is even after reboot and doing several fsck of the
>> ext4fs
>> the file size "occupied" is more than the pool size. How is this ?
>> I agree that data may be corrupted, but there *is* some data and this
>> must be
>> saved somewhere. Why is this "somewhere" exceeding the pool size ?
>>
>
> Hi
>
> Few key principles -
>
>
> 1. You should always mount extX fs with  errors=remount-ro  (tune2fs,mount)
>
> 2. There are few data={} modes ensuring various degree of data integrity,
>    An case you really care about data integrity here - switch to 'journal'
>    mode at price of lower speed. Default ordered mode might show this.
>    (i.e. it's the very same behavior as you would have seen with failing
> hdd)
>
> 3. Do not continue using thin-pool when it's full :)
>
> 4. We do miss more configurable policies with thin-pools.
>    i.e. do plan to instantiate 'error' target for writes in the case
>    pool gets full - so ALL writes will be errored - as of now - writes
>    to provisioned blocks may cause further filesystem confusion - that's
>    why  'remount-ro' is rather mandatory - xfs is recently being enhanced
>    to provide similar logic.
>
>
>
> Regards
>
>
> Zdenek
>
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>
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