On 03/07 2014 06:59 AM, Dave Chinner wrote:
> On Thu, Mar 06, 2014 at 06:15:27PM +0900, Yongmin wrote:
>>
>> Hello.
>>
>> My name is Yongmin Park and I am a graduated student in Ajou University
>> (Korea).
>> My research area is Digital Forensics.
>> And this time i tried to understand the structure of XFS file system,
>> because XFS is one of the famous huge file system in these days.
>>
>> I already founded and read 'XFS Filesystem Structure 2nd Edition Revision 1'
>> on the Internet, which was written by Silicon Graphics Inc in 2006 and it is
>> really well written to understand.
>>
>> But the concentrated part of mine is "Deleted File Recovery", so the
>> Journaling part is really important for me,, but regretfully there are no
>> specific guide line about Journaling part...
>> Also next version(maybe the 3re Edition) is not exsist for more than a 5
>> years.
>>
>> So is there no guide line for journaling part in XFS?
>> How can i get them,, have I to buy them? or Is Analysing Source Cord only
>> way to study?
>
> There is some documentation about some of the logging concepts and
> design. eg:
>
> http://oss.sgi.com/cgi-bin/gitweb.cgi?p=xfs/xfs-documentation.git;a=blob;f=design/xfs-delayed-logging-design.asciidoc
Not sure if someone else also think that XFS journal design is the
stumbling-block
to get involved into the development...but I once heard of "I'm really confused
by
the design of delayed logging, I have to give up after reading the document for
about
2 or 3 weeks..." from 2 Chinese developers in the past year, though nothing can
help
someone out without taking infinite patience.
>
> But the only way to learn about the actual structure of the log is to
> read the code and use xfs_logprint to study the contents of the log.
To Yongmin,
For your information only.
I'm trying to understand XFS journal via the following steps:
1) Download Linux-2.6.34 source, read the journal code.
Understand the original design as there is no delayed-logging support at that
time.
FYI, two obsoleted documents could be found at,
http://oss.sgi.com/projects/xfs/design_docs/xfsdocs93_pdf/log_mgr-overview.pdf
http://oss.sgi.com/projects/xfs/design_docs/xfsdocs93_pdf/log_mgr.pdf
2) Download Linux-2.6.35 source, read the journal code and
delayed-logging-design doc as
per Dave's suggestion because we have this big change in this version.
3) Play with xfs_logprint with the XFS mainline source and read all those
threads in XFS
mailing list which are related to journals in the past several years....
4) Nothing, just have fun. :)
Thanks,
-Jeff
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