Re: [Gluster-users] Bit rot disabled as default

[Gandalf Corvotempesta]

Il 15 giu 2016 18:13, "Дмитрий Глушенок"  ha scritto:
>
> Hello.
>
> May be because of current implementation of rotten bits detection - one
hash for whole file. Imagine 40 GB VM image - few parts of the image are
modified continuously (VM log files and application data are constantly
changing). Those writes making checksum invalid and BitD has to recalculate
it endlessly. As the result - checksum of VM image can never be verified.
>

And what about enabling bitrot for small files like emails in a maildir?
in this case the bitrot feature with 1 hash for the whole file would be ok.
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Re: [Gluster-users] Bit rot disabled as default

[Gandalf Corvotempesta]

2016-06-15 21:29 GMT+02:00 Дмитрий Глушенок :
> Sharding almost solves the problem (for inactive blocks), but it was
> considered as stable just today :)

I've predicted the future :)
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Re: [Gluster-users] Bit rot disabled as default

[Дмитрий Глушенок]

Sharding almost solves the problem (for inactive blocks), but it was considered 
as stable just today :)

http://blog.gluster.org/2016/06/glusterfs-3-8-released/ 

- Sharding is now stable for VM image storage.

--
Dmitry Glushenok
Jet Infosystems

> 15 июня 2016 г., в 19:42, Gandalf Corvotempesta 
>  написал(а):
> 
> 2016-06-15 18:12 GMT+02:00 Дмитрий Глушенок :
>> Hello.
>> 
>> May be because of current implementation of rotten bits detection - one hash
>> for whole file. Imagine 40 GB VM image - few parts of the image are modified
>> continuously (VM log files and application data are constantly changing).
>> Those writes making checksum invalid and BitD has to recalculate it
>> endlessly. As the result - checksum of VM image can never be verified.
> 
> I think you are right
> But what about sharding? In this case, the hash should be created for
> each shard and not the whole file.

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Re: [Gluster-users] Bit rot disabled as default

[Gandalf Corvotempesta]

2016-06-15 18:12 GMT+02:00 Дмитрий Глушенок :
> Hello.
>
> May be because of current implementation of rotten bits detection - one hash
> for whole file. Imagine 40 GB VM image - few parts of the image are modified
> continuously (VM log files and application data are constantly changing).
> Those writes making checksum invalid and BitD has to recalculate it
> endlessly. As the result - checksum of VM image can never be verified.

I think you are right
But what about sharding? In this case, the hash should be created for
each shard and not the whole file.
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Re: [Gluster-users] Bit rot disabled as default

[Дмитрий Глушенок]

Hello.

May be because of current implementation of rotten bits detection - one hash 
for whole file. Imagine 40 GB VM image - few parts of the image are modified 
continuously (VM log files and application data are constantly changing). Those 
writes making checksum invalid and BitD has to recalculate it endlessly. As the 
result - checksum of VM image can never be verified.

> 15 июня 2016 г., в 9:37, Gandalf Corvotempesta 
>  написал(а):
> 
> I was looking at docs.
> why bit rot protection is disabled by defaults?
> with huge files like a qcow image a bit rot could lead to the whole image 
> corrupted and replicated to the whole cluster
> 
> Any drawbacks with bit rot detection to explain the default to off?
> 
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--
Dmitry Glushenok
Jet Infosystems

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[Gluster-users] Bit rot disabled as default

[Gandalf Corvotempesta]

I was looking at docs.
why bit rot protection is disabled by defaults?
with huge files like a qcow image a bit rot could lead to the whole image
corrupted and replicated to the whole cluster

Any drawbacks with bit rot detection to explain the default to off?
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