Re: [rgw multisite] disable specified bucket data sync

Re: [rgw multisite] disable specified bucket data sync

[Zhangzengran]

>> Hi Casey:
>>          Why don’t support stopping specified bucket data sync. Is there any difficulty in implementing the feature?
>>          Or am I missing something?
>>
>>          Thank you !
>
>
>Hi,
>
>What would you like to get out of this feature? A way to disable sync on a given bucket temporarily, and turn it back on later? Or just a way to have a subset of buckets that don't ever participate in sync?
>
>Do you have a use case for the first? That's not something we'd considered.
>
>If you just want to have some buckets that never sync, you might consider serving those out of a separate gateway, in a zone that isn't part of a multisite configuration.
>
>Thanks,
>Casey

deploy a separate none-sync zone with different endpoint may not a good choice. we hope enable/disable a specified bucket sync could be somewhat flexible. :)
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Re: [rgw multisite] disable specified bucket data sync

[Casey Bodley]

The ability to disable sync per-bucket could certainly be added, but it 
would take some work to get right.

First you'd need a radosgw-admin command to enable/disable sync on a 
given bucket, and store that flag with the bucket instance. We read the 
bucket instance before starting sync on each bucket, so you could skip 
the sync depending on that flag.

However, each zone is trying to sync data from all other zones in its 
zonegroup. So disabling it on zone A, for example, will only prevent 
zone A from pulling changes from other zones. The other zones would 
still be pulling changes from zone A, because they have their own copy 
of the bucket instance. So you'd probably want some way to coordinate 
this setting between zones.

The other challenge would be in the interaction with the 'data changes 
log'. Each zone maintains a log of bucket names that have local changes 
(you can view this with 'radosgw-admin datalog list'). Other zones read 
from this log to decide which buckets they need to sync. However, say 
that zone A reads about a change to bucket1 on zone B. If sync on 
bucket1 is disabled, zone A skips the sync and advances its position in 
zone B's datalog. So if sync on bucket1 is later enabled, zone A won't 
remember that it needs to sync from B.

So I think the trick would be to add special entries to the datalog when 
buckets are enabled/disabled, so that other zones will know to a) update 
their local bucket instance, and b) restart sync if enabled. We might 
also want to restrict the radosgw-admin command to the zonegroup's 
master zone so we can avoid races between enable/disable from different 
zones.

Casey


On 08/02/2016 09:16 PM, Zhangzengran wrote:
>>> Hi Casey:
>>>           Why don’t support stopping specified bucket data sync. Is there any difficulty in implementing the feature?
>>>           Or am I missing something?
>>>
>>>           Thank you !
>>
>> Hi,
>>
>> What would you like to get out of this feature? A way to disable sync on a given bucket temporarily, and turn it back on later? Or just a way to have a subset of buckets that don't ever participate in sync?
>>
>> Do you have a use case for the first? That's not something we'd considered.
>>
>> If you just want to have some buckets that never sync, you might consider serving those out of a separate gateway, in a zone that isn't part of a multisite configuration.
>>
>> Thanks,
>> Casey
> deploy a separate none-sync zone with different endpoint may not a good choice. we hope enable/disable a specified bucket sync could be somewhat flexible. :)
> -------------------------------------------------------------------------------------------------------------------------------------
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> 邮件！
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> disclosure, reproduction, or dissemination) by persons other than the intended
> recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender
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Re: [rgw multisite] disable specified bucket data sync

[Yehuda Sadeh-Weinraub]

On Mon, Aug 15, 2016 at 1:48 PM, Casey Bodley <cbodley@redhat.com> wrote:
> The ability to disable sync per-bucket could certainly be added, but it
> would take some work to get right.
>
> First you'd need a radosgw-admin command to enable/disable sync on a given
> bucket, and store that flag with the bucket instance. We read the bucket
> instance before starting sync on each bucket, so you could skip the sync
> depending on that flag.

That would be the bucket info (that corresponds to a specific bucket instance).

>
> However, each zone is trying to sync data from all other zones in its
> zonegroup. So disabling it on zone A, for example, will only prevent zone A
> from pulling changes from other zones. The other zones would still be
> pulling changes from zone A, because they have their own copy of the bucket
> instance. So you'd probably want some way to coordinate this setting between

Not quite. The bucket info is a metadata entity, so it's being
modified on the master and synced to all other zones. Similar to other
bucket metadata changes, we can have the zone where the change is
requested on forward the request to the master.

> zones.
>
> The other challenge would be in the interaction with the 'data changes log'.
> Each zone maintains a log of bucket names that have local changes (you can
> view this with 'radosgw-admin datalog list'). Other zones read from this log
> to decide which buckets they need to sync. However, say that zone A reads
> about a change to bucket1 on zone B. If sync on bucket1 is disabled, zone A
> skips the sync and advances its position in zone B's datalog. So if sync on
> bucket1 is later enabled, zone A won't remember that it needs to sync from
> B.

Yeah, need to add entry to the data log whenever we enable (not sure
about disable) sync on a bucket.

>
> So I think the trick would be to add special entries to the datalog when
> buckets are enabled/disabled, so that other zones will know to a) update
> their local bucket instance, and b) restart sync if enabled. We might also
> want to restrict the radosgw-admin command to the zonegroup's master zone so
> we can avoid races between enable/disable from different zones.

We should do it the same way we do other bucket metadata changes,
potentially just reuse that code path.

>

One thing that I would do differently is that instead of having a
single flag on the bucket info to specify whether a bucket is getting
synced or not, I'd have a more detailed mapping of different zone
relationships. For each zone it'd specify which zones it's syncing
this bucket from. By default the map will be empty, and there will be
another flag that will override it that will just mean 'sync from all'
(default as true). This is pretty much in line with some changes that
I'm planning for the zones themselves, so having a per-bucket sync
config makes sense. It'll also be a step towards implementing the
swift container sync api.

Yehuda

> Casey
>
>
>
> On 08/02/2016 09:16 PM, Zhangzengran wrote:
>>>>
>>>> Hi Casey:
>>>>           Why don’t support stopping specified bucket data sync. Is
>>>> there any difficulty in implementing the feature?
>>>>           Or am I missing something?
>>>>
>>>>           Thank you !
>>>
>>>
>>> Hi,
>>>
>>> What would you like to get out of this feature? A way to disable sync on
>>> a given bucket temporarily, and turn it back on later? Or just a way to have
>>> a subset of buckets that don't ever participate in sync?
>>>
>>> Do you have a use case for the first? That's not something we'd
>>> considered.
>>>
>>> If you just want to have some buckets that never sync, you might consider
>>> serving those out of a separate gateway, in a zone that isn't part of a
>>> multisite configuration.
>>>
>>> Thanks,
>>> Casey
>>
>> deploy a separate none-sync zone with different endpoint may not a good
>> choice. we hope enable/disable a specified bucket sync could be somewhat
>> flexible. :)
>>
>> -------------------------------------------------------------------------------------------------------------------------------------
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>> which is
>> intended only for the person or entity whose address is listed above. Any
>> use of the
>> information contained herein in any way (including, but not limited to,
>> total or partial
>> disclosure, reproduction, or dissemination) by persons other than the
>> intended
>> recipient(s) is prohibited. If you receive this e-mail in error, please
>> notify the sender
>> by phone or email immediately and delete it!
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Re: [rgw multisite] disable specified bucket data sync

[Zhangzengran]

I have some different ideas, but i do not know whether or not feasible.

right now the data sync is based on data-change log and bilog, and whole buckets'both logs
logged depending on zone'log_data flag . So i think, we could stop logging the specified bucket's bilog and
data-change log,when we want to disable its data sync. Thus we modify the log logic instead of sync logic.
enable/disable log also depend on a new flag in bucket info, which modified by a new rgw-admin command.

Separating the feature from sync logic maybe help to simplify furture zones changes.

Thanks
>On Mon, Aug 15, 2016 at 1:48 PM, Casey Bodley <cbodley@redhat.com> wrote:
>> The ability to disable sync per-bucket could certainly be added, but
>> it would take some work to get right.
>>
>> First you'd need a radosgw-admin command to enable/disable sync on a
>> given bucket, and store that flag with the bucket instance. We read
>> the bucket instance before starting sync on each bucket, so you could
>> skip the sync depending on that flag.
>
>That would be the bucket info (that corresponds to a specific bucket instance).
>
>>
>> However, each zone is trying to sync data from all other zones in its
>> zonegroup. So disabling it on zone A, for example, will only prevent
>> zone A from pulling changes from other zones. The other zones would
>> still be pulling changes from zone A, because they have their own copy
>> of the bucket instance. So you'd probably want some way to coordinate
>> this setting between
>
>Not quite. The bucket info is a metadata entity, so it's being modified on the master and synced to all other zones. Similar to other bucket metadata changes, we can have the zone where the change is requested on forward the request to the master.
>
>> zones.
>>
>> The other challenge would be in the interaction with the 'data changes log'.
>> Each zone maintains a log of bucket names that have local changes (you
>> can view this with 'radosgw-admin datalog list'). Other zones read
>> from this log to decide which buckets they need to sync. However, say
>> that zone A reads about a change to bucket1 on zone B. If sync on
>> bucket1 is disabled, zone A skips the sync and advances its position
>> in zone B's datalog. So if sync on
>> bucket1 is later enabled, zone A won't remember that it needs to sync
>> from B.
>
>Yeah, need to add entry to the data log whenever we enable (not sure about disable) sync on a bucket.
>
>>
>> So I think the trick would be to add special entries to the datalog
>> when buckets are enabled/disabled, so that other zones will know to a)
>> update their local bucket instance, and b) restart sync if enabled. We
>> might also want to restrict the radosgw-admin command to the
>> zonegroup's master zone so we can avoid races between enable/disable from different zones.
>
>We should do it the same way we do other bucket metadata changes, potentially just reuse that code path.
>
>>
>
>One thing that I would do differently is that instead of having a single flag on the bucket info to specify whether a bucket is getting synced or not, I'd have a more detailed mapping of different zone relationships. For each zone it'd specify which zones it's syncing this bucket from. By default the map will be empty, and there will be another flag that will override it that will just mean 'sync from all'
>(default as true). This is pretty much in line with some changes that I'm planning for the zones themselves, so having a per-bucket sync config makes sense. It'll also be a step towards implementing the swift container sync api.
>
>Yehuda
>
>> Casey
>>
>>
>>
>> On 08/02/2016 09:16 PM, Zhangzengran wrote:
>>>>>
>>>>> Hi Casey:
>>>>>           Why don’t support stopping specified bucket data sync. Is
>>>>> there any difficulty in implementing the feature?
>>>>>           Or am I missing something?
>>>>>
>>>>>           Thank you !
>>>>
>>>>
>>>> Hi,
>>>>
>>>> What would you like to get out of this feature? A way to disable
>>>> sync on a given bucket temporarily, and turn it back on later? Or
>>>> just a way to have a subset of buckets that don't ever participate in sync?
>>>>
>>>> Do you have a use case for the first? That's not something we'd
>>>> considered.
>>>>
>>>> If you just want to have some buckets that never sync, you might
>>>> consider serving those out of a separate gateway, in a zone that
>>>> isn't part of a multisite configuration.
>>>>
>>>> Thanks,
>>>> Casey
>>>
>>> deploy a separate none-sync zone with different endpoint may not a
>>> good choice. we hope enable/disable a specified bucket sync could be
>>> somewhat flexible. :)
>>>


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Re: [rgw multisite] disable specified bucket data sync

[Casey Bodley]

On 08/02/2016 03:34 AM, Zhangzengran wrote:
> Hi Casey:
>          Why don’t support stopping specified bucket data sync. Is there any difficulty in implementing the feature?
>          Or am I missing something?
>
>          Thank you !
> -------------------------------------------------------------------------------------------------------------------------------------
> 本邮件及其附件含有杭州华三通信技术有限公司的保密信息，仅限于发送给上面地址中列出
> 的个人或群组。禁止任何其他人以任何形式使用（包括但不限于全部或部分地泄露、复制、
> 或散发）本邮件中的信息。如果您错收了本邮件，请您立即电话或邮件通知发件人并删除本
> 邮件！
> This e-mail and its attachments contain confidential information from H3C, which is
> intended only for the person or entity whose address is listed above. Any use of the
> information contained herein in any way (including, but not limited to, total or partial
> disclosure, reproduction, or dissemination) by persons other than the intended
> recipient(s) is prohibited. If you receive this e-mail in error, please notify the sender
> by phone or email immediately and delete it!

Hi,

What would you like to get out of this feature? A way to disable sync on 
a given bucket temporarily, and turn it back on later? Or just a way to 
have a subset of buckets that don't ever participate in sync?

Do you have a use case for the first? That's not something we'd considered.

If you just want to have some buckets that never sync, you might 
consider serving those out of a separate gateway, in a zone that isn't 
part of a multisite configuration.

Thanks,
Casey

[rgw multisite] disable specified bucket data sync

[Zhangzengran]

Hi Casey:
        Why don’t support stopping specified bucket data sync. Is there any difficulty in implementing the feature?
        Or am I missing something?

        Thank you !
-------------------------------------------------------------------------------------------------------------------------------------
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