[Ocfs-users] Re: About compression of files on OCFS

[Drew McCarthy]

Kenichiro,
When you write  to an OCFS partition you need your application to use 
the O_DIRECT flag which causes the write to bypass the kernel cache.
Therefore if your compression tool is capable of using the O_DIRECT flag 
it should be able to write to an OCFS partition.

I did a quick search on gzip and could not find any information that 
indicates it can use the O_DIRECT flag, based on this quick search I 
would say that you cannot use gzip to compress files on an OCFS partition.
If you perform a search on any other compression algorithm and it does 
not allow you to use O_DIRECT then you can assume it wont work with OCFS.



Sunil Mushran wrote:

> Again, it's not the act of compression but rather the mode of r/w.
> If one writes a compress tool which is o_direct, then I see no issue.
>
> Kenichiro Ochi wrote:
>
>> Sunil
>> Thank you for your prompt reply.
>> I really appreciate it.
>>
>> Please let me know if you know.
>> Do you know the documentation which shows as follwing.
>> - It is not supported that archive logfiles on OCFS are compressed.
>>
>> Thank you in advance.
>>
>> Thanks.
>> Kenichiro
>>
>>
>> On Thu, 28 Jul 2005 12:05:16 -0700
>> Sunil Mushran <Sunil.Mushran at oracle.com> wrote:
>>
>>  
>>
>>> The issue is not the type of files, rather the mode the files are r/w.
>>> OCFS (Release 1) is supported only for o_direct operations.
>>> gzip, etc. do bufferred reads and hence is an issue.
>>>
>>> Kenichiro Ochi wrote:
>>>
>>>   
>>>
>>>> Hi, Experts.
>>>> I'm Kenichiro Ochi, the support engineer of Oracle Japan.
>>>>
>>>> I would like to ask you the following questions about supported 
>>>> files on OCFS.
>>>> I know OCFS VER 1.X only supports Oracle datafiles (including 
>>>> archive logfiles).
>>>>
>>>> My customer has one question.
>>>>
>>>> - Is it supported that archive logfiles on OCFS are compressed 
>>>>  (using compress, gzip command etc) ?
>>>>  In other words, is it allowed that there are compressed files(.Z, 
>>>> .zip etc) on OCFS ?
>>>>
>>>> I would appreciate it if I could receive feedback on it at your 
>>>> earliest convenience.
>>>>
>>>> Since I'm not in the mailing list, please reply directly back to me.
>>>> Thank you in advance.
>>>>
>>>> Thanks
>>>> Kenichiro
>>>>
>>>>
>>>>
>>>>
>>>>     
>>>
>>
>>  
>>
>

-- 
Regards Drew

____________________________________________________________
Drew McCarthy
Senior Principal Solution Consultant
Oracle On Demand - Australia

Phone           +61 3 8616 4135
Fax             +61 3 9699 1259
Mobile          +61 414 637 473

AIM             GuinessMagic

Oracle Corporation
Level 7, 324 St Kilda Road
Melbourne, VIC  
Australia 3004
____________________________________________________________

This communication contains information which is confidential and may
also be privileged.  It is for the exclusive use of the intended
recipient(s).
If you are not the intended recipient(s), please note that any
distribution, copying or use of this communication or the information in it is
strictly prohibited.  If you have received this communication in error, please
notify the sender immediately and then destroy any copies of it.