Re: ALTER DATABASE ARCHIVELOG COMPRESS ENABLE

Well, file system compression is a rather old technology, pioneered by Microsoft. I remember compressing my "Documents" folder on XP. It's actually rather strange that server file systems like ACFS and XFS needed so long to catch up.
Regards

Mladen Gogala

On Fri, Dec 21, 2018, 7:14 PM Luis Santos <lsantos_at_pobox.com wrote:

> Andy, thanks for the reply.
>
> As far I researched ACFS compression option is supported for all databases
> files. It just doesn't work (it's null!) for online redo logs and control
> files.
>
> In other words: online redo logs and control file are never compressed,
> even when stored into a compressed on ACFS filesystem. This is not a
> problem, as these files are, in general, a small fraction of the database
> full storage. And this is reasonable, as these files must have small, fast
> and synced writes. Not the ideal environment for an on-the-fly compression.
>
> By the way, I'm interested now just in compression for archived redo logs,
> which large, async, once write batch are, IMHO, perfect for on-the-fly
> compression.
>
> Thanks anyway for enrich the conversation.
>
> *--*
> *Att*
>
>
> *Luis Santos*
>
>
>
> Em sex, 21 de dez de 2018 às 14:50, Andy Wattenhofer <watt0012_at_umn.edu>
> escreveu:
>
>> For the sake of completeness, it appears that ACFS compression *is*
>> supported for database files. I had to check, because some ACFS features
>> are not supported for database files where there is a paid alternative
>> option such as Database Vault. See the full list in the chart here (scroll
>> down to the ACFS row):
>> https://docs.oracle.com/database/121/DBLIC/editions.htm#GUID-75262092-CD86-4B30-A21B-92ECC1C2E130
>>
>>
>> Andy
>>
>> On Fri, Dec 21, 2018 at 6:41 AM Luis Santos <lsantos_at_pobox.com> wrote:
>>
>>> Niall, thanks for your input.
>>>
>>> I was just researching about it just after I have sent my previous email.
>>>
>>> http://afatkulin.blogspot.com/2017/07/122-acfs-compression-part-i.html
>>>
>>> Yes, this can be a reasonable solution. And supported too!
>>>
>>> I just can't figure out why compression is just an ACFS option. Why not
>>> also a Disk Group attribute?
>>>
>>>
>>> *--*
>>> *Att*
>>>
>>>
>>> *Luis Santos*
>>>
>>>
>>>
>>> Em sex, 21 de dez de 2018 às 10:04, <niall.litchfield_at_gmail.com>
>>> escreveu:
>>>
>>>> In the case of ASM you could always provision an ACFS filesystem which
>>>> also supports compression since 12.2,:). I'd be wary of using a feature
>>>> that's been around since 10 and never made it to documented status when
>>>> there are supported alternative options.
>>>>
>>>> On Fri, Dec 21, 2018 at 10:26 AM Luis Santos <lsantos_at_pobox.com> wrote:
>>>>
>>>>> I'm aware of on-the-fly compression filesystems since old Windows
>>>>> Stacker.
>>>>>
>>>>> This is not an option for Oracle DBs in ASM.
>>>>>
>>>>> But thanks anyway!
>>>>>
>>>>>
>>>>> *--*
>>>>> *Att*
>>>>>
>>>>>
>>>>> *Luis Santos*
>>>>>
>>>>>
>>>>>
>>>>> Em qui, 20 de dez de 2018 às 17:01, Mladen Gogala <
>>>>> gogala.mladen_at_gmail.com> escreveu:
>>>>>
>>>>>> Ah that!
>>>>>>
>>>>>> That too is supported:
>>>>>>
>>>>>> https://www.redhat.com/en/blog/look-vdo-new-linux-compression-layer
>>>>>>
>>>>>> You can have a compressed file system and put your archive logs
>>>>>> there. NTFS too has such capability. There is no reason for Oracle to do
>>>>>> compression of the archive logs. I prefer rman to maintain cleanliness of
>>>>>> my LOG_ARCHIVE_DEST_1. And cleanliness is next to godliness.
>>>>>>
>>>>>> Regards
>>>>>>
>>>>>>
>>>>>> On 12/20/18 1:16 PM, Luis Santos wrote:
>>>>>>
>>>>>> This relates to on-the-fly compression on redo log transport between
>>>>>> Data Guard DB nodes.
>>>>>>
>>>>>> --
>>>>>> Mladen Gogala
>>>>>> Database Consultant
>>>>>> Tel: (347) 321-1217
>>>>>>
>>>>>>
>>>>
>>>> --
>>>> Niall Litchfield
>>>> Oracle DBA
>>>> http://www.orawin.info
>>>>
>>>

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