zfs discuss - Oct 2008 - zdb to dump data

Is there some hidden way to coax zdb into not just displaying data based on a
given DVA but rather to dump it in raw usable form?

I''ve got a pool with large amounts of corruption.  Several directories
are toast and I get "I/O Error" when trying to enter or read the
directory... however I can read the directory and files using ZDB, if I could
just dump it in a raw format I could do recovery that way.

To be clear, I''ve already recovered from the situation, this is purely
an academic "can I do it" exercise for the sake of learning.

If ZDB can''t do it, I''d assume I''d have to write some
code to read based on DVA.  Maybe I could write a little tool for it.

benr.
-- 
This message posted from opensolaris.org

Hi Ben,

Ben Rockwood ?????:
> Is there some hidden way to coax zdb into not just displaying data
> based on a given DVA but rather to dump it in raw usable form?
> 
> I''ve got a pool with large amounts of corruption.  Several
> directories are toast and I get "I/O Error" when trying to enter
or
> read the directory... however I can read the directory and files
> using ZDB, if I could just dump it in a raw format I could do
> recovery that way.
> 
> To be clear, I''ve already recovered from the situation, this is
> purely an academic "can I do it" exercise for the sake of
learning.
> 
> If ZDB can''t do it, I''d assume I''d have to write
some code to read
> based on DVA.  Maybe I could write a little tool for it.
zdb -R can read raw data blocks from the pool if flag ''r'' is
used, so if
you can identify list of a blocks comprising some file, you can feed it 
to zdb -R.

See comments in zdb source (before zdb_read_block()) for exact syntax.

Wbr,
Victor

max at bruningsystems.com ?????:
> Hi,
> Victor Latushkin wrote:
>> Hi Ben,
>>
>> Ben Rockwood ?????:
>>  
>>> Is there some hidden way to coax zdb into not just displaying data
>>> based on a given DVA but rather to dump it in raw usable form?
>>>
>>> I''ve got a pool with large amounts of corruption.  Several
>>> directories are toast and I get "I/O Error" when trying
to enter or
>>> read the directory... however I can read the directory and files
>>> using ZDB, if I could just dump it in a raw format I could do
>>> recovery that way.
>>>
>>> To be clear, I''ve already recovered from the situation,
this is
>>> purely an academic "can I do it" exercise for the sake of
learning.
>>>
>>> If ZDB can''t do it, I''d assume I''d have
to write some code to read
>>> based on DVA.  Maybe I could write a little tool for it.
>>>     
>>
>> zdb -R can read raw data blocks from the pool if flag
''r'' is used, so
>> if you can identify list of a blocks comprising some file, you can 
>> feed it to zdb -R.
>>
>>   
> I have decided to file an RFE so that zdb with the -R option will
> allow one to decompress data before dumping it. I have had this
> implemented for several months now, and was told that a way to get it
> into opensolaris was to file an RFE. However, when I go to file the 
> RFE, after typing in the information and hitting "send", I am
> getting: >
> 
>  Not Found
> 
> The requested URL /bug/os was not found on this server.
> 
> ------------------------------------------------------------------------
> Apache/2.0.58 (Unix) mod_ssl/2.0.58 OpenSSL/0.9.8a DAV/2 proxy_html/2.5 
> mod_jk/1.2.15 Server at www.opensolaris.org Port 80
> 
> Any ideas?
I have no idea whatmay be wrong with web-site, but there''s already RFE

6757444 want zdb -R to support decompression, checksumming and raid-z

regards,
victor
> thanks,
> max

Hi,
Victor Latushkin wrote:
> Hi Ben,
>
> Ben Rockwood ?????:
>   
>> Is there some hidden way to coax zdb into not just displaying data
>> based on a given DVA but rather to dump it in raw usable form?
>>
>> I''ve got a pool with large amounts of corruption.  Several
>> directories are toast and I get "I/O Error" when trying to
enter or
>> read the directory... however I can read the directory and files
>> using ZDB, if I could just dump it in a raw format I could do
>> recovery that way.
>>
>> To be clear, I''ve already recovered from the situation, this
is
>> purely an academic "can I do it" exercise for the sake of
learning.
>>
>> If ZDB can''t do it, I''d assume I''d have to
write some code to read
>> based on DVA.  Maybe I could write a little tool for it.
>>     
>
> zdb -R can read raw data blocks from the pool if flag ''r''
is used, so if
> you can identify list of a blocks comprising some file, you can feed it 
> to zdb -R.
>
>   
I have decided to file an RFE so that zdb with the -R option will allow 
one to decompress
data before dumping it.  I have had this implemented for several months 
now, and was told that
a way to get it into opensolaris was to file an RFE.  However, when I go 
to file the
RFE, after typing in the information and hitting "send", I am getting:


  Not Found

The requested URL /bug/os was not found on this server.

------------------------------------------------------------------------
Apache/2.0.58 (Unix) mod_ssl/2.0.58 OpenSSL/0.9.8a DAV/2 proxy_html/2.5 
mod_jk/1.2.15 Server at www.opensolaris.org Port 80

Any ideas?
thanks,
max

> See comments in zdb source (before zdb_read_block()) for exact syntax.
>
> Wbr,
> Victor
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>

Victor Latushkin wrote:
> max at bruningsystems.com ?????:
>> Hi,
>> Victor Latushkin wrote:
>>> Hi Ben,
>>>
>>> Ben Rockwood ?????:
>>>  
>>>> Is there some hidden way to coax zdb into not just displaying
data
>>>> based on a given DVA but rather to dump it in raw usable form?
>>>>
>>>> I''ve got a pool with large amounts of corruption. 
Several
>>>> directories are toast and I get "I/O Error" when
trying to enter or
>>>> read the directory... however I can read the directory and
files
>>>> using ZDB, if I could just dump it in a raw format I could do
>>>> recovery that way.
>>>>
>>>> To be clear, I''ve already recovered from the
situation, this is
>>>> purely an academic "can I do it" exercise for the
sake of learning.
>>>>
>>>> If ZDB can''t do it, I''d assume I''d
have to write some code to read
>>>> based on DVA.  Maybe I could write a little tool for it.
>>>>     
>>>
>>> zdb -R can read raw data blocks from the pool if flag
''r'' is used,
>>> so if you can identify list of a blocks comprising some file, you 
>>> can feed it to zdb -R.
>>>
>>>   
>> I have decided to file an RFE so that zdb with the -R option will
>> allow one to decompress data before dumping it. I have had this
>> implemented for several months now, and was told that a way to get it
>> into opensolaris was to file an RFE. However, when I go to file the 
>> RFE, after typing in the information and hitting "send", I am
>> getting: >
>>
>>  Not Found
>>
>> The requested URL /bug/os was not found on this server.
>>
>>
------------------------------------------------------------------------
>> Apache/2.0.58 (Unix) mod_ssl/2.0.58 OpenSSL/0.9.8a DAV/2 
>> proxy_html/2.5 mod_jk/1.2.15 Server at www.opensolaris.org Port 80
>>
>> Any ideas?
>
> I have no idea whatmay be wrong with web-site, but there''s already
RFE
>
> 6757444 want zdb -R to support decompression, checksumming and raid-z
>
> regards,
> victor
>
Thanks Victor.  I guess searching the bug/rfe site for zdb is not the 
correct way to find
this.  I looked for keyword: zdb and text: decompress
and got no hits.  Maybe I should have used google...

max

max at bruningsystems.com ?????:
> Victor Latushkin wrote:
>> max at bruningsystems.com ?????:
>>> Hi,
>>> Victor Latushkin wrote:
>>>> Hi Ben,
>>>>
>>>> Ben Rockwood ?????:
>>>>  
>>>>> Is there some hidden way to coax zdb into not just
displaying data
>>>>> based on a given DVA but rather to dump it in raw usable
form?
>>>>>
>>>>> I''ve got a pool with large amounts of corruption. 
Several
>>>>> directories are toast and I get "I/O Error" when
trying to enter or
>>>>> read the directory... however I can read the directory and
files
>>>>> using ZDB, if I could just dump it in a raw format I could
do
>>>>> recovery that way.
>>>>>
>>>>> To be clear, I''ve already recovered from the
situation, this is
>>>>> purely an academic "can I do it" exercise for the
sake of learning.
>>>>>
>>>>> If ZDB can''t do it, I''d assume
I''d have to write some code to read
>>>>> based on DVA.  Maybe I could write a little tool for it.
>>>>>     
>>>>
>>>> zdb -R can read raw data blocks from the pool if flag
''r'' is used,
>>>> so if you can identify list of a blocks comprising some file,
you
>>>> can feed it to zdb -R.
>>>>
>>>>   
>>> I have decided to file an RFE so that zdb with the -R option will
>>> allow one to decompress data before dumping it. I have had this
>>> implemented for several months now, and was told that a way to get
it
>>> into opensolaris was to file an RFE. However, when I go to file the
>>> RFE, after typing in the information and hitting "send",
I am
>>> getting: >
>>>
>>>  Not Found
>>>
>>> The requested URL /bug/os was not found on this server.
>>>
>>>
------------------------------------------------------------------------
>>> Apache/2.0.58 (Unix) mod_ssl/2.0.58 OpenSSL/0.9.8a DAV/2 
>>> proxy_html/2.5 mod_jk/1.2.15 Server at www.opensolaris.org Port 80
>>>
>>> Any ideas?
>>
>> I have no idea whatmay be wrong with web-site, but there''s
already RFE
>>
>> 6757444 want zdb -R to support decompression, checksumming and raid-z
>>
>> regards,
>> victor
>>
> Thanks Victor.  I guess searching the bug/rfe site for zdb is not the 
> correct way to find
> this.  I looked for keyword: zdb and text: decompress
> and got no hits.  Maybe I should have used google...
Search for keyword ''zdb'' returns only one result, but search
for text
''zdb'' returns a lot. I guess keywords search depends on
keywords being
there.

victor

Victor Latushkin wrote:
> max at bruningsystems.com ?????:
>> Hi,
>> Victor Latushkin wrote:
>>> Hi Ben,
>>>
>>> Ben Rockwood ?????:
>>>
>>>> Is there some hidden way to coax zdb into not just displaying
data
>>>> based on a given DVA but rather to dump it in raw usable form?
>>>>
>>>> I''ve got a pool with large amounts of corruption.
Several
>>>> directories are toast and I get "I/O Error" when
trying to enter or
>>>> read the directory... however I can read the directory and
files
>>>> using ZDB, if I could just dump it in a raw format I could do
>>>> recovery that way.
>>>>
>>>> To be clear, I''ve already recovered from the
situation, this is
>>>> purely an academic "can I do it" exercise for the
sake of learning.
>>>>
>>>> If ZDB can''t do it, I''d assume I''d
have to write some code to read
>>>> based on DVA. Maybe I could write a little tool for it.
>>>>
>>> zdb -R can read raw data blocks from the pool if flag
''r'' is used, so
>>> if you can identify list of a blocks comprising some file, you can
>>> feed it to zdb -R.
>>>
>>>
>> I have decided to file an RFE so that zdb with the -R option will
>> allow one to decompress data before dumping it. I have had this
>> implemented for several months now, and was told that a way to get it
>> into opensolaris was to file an RFE. However, when I go to file the
>> RFE, after typing in the information and hitting "send", I am
>> getting: >
>>
>> Not Found
>>
>> The requested URL /bug/os was not found on this server.
>>
>>
------------------------------------------------------------------------
>> Apache/2.0.58 (Unix) mod_ssl/2.0.58 OpenSSL/0.9.8a DAV/2 proxy_html/2.5
>> mod_jk/1.2.15 Server at www.opensolaris.org Port 80
>>
>> Any ideas?
>
So you are unable to submit a bug?

When did this happen (date/time)?

I will check the logs.

Derek
> I have no idea whatmay be wrong with web-site, but there''s already
RFE
>
> 6757444 want zdb -R to support decompression, checksumming and raid-z
>
> regards,
> victor
>
>> thanks,
>> max
>
>
>
> _______________________________________________
> website-discuss mailing list
> website-discuss at opensolaris.org

Hi Derek,
Derek Cicero wrote:
> Victor Latushkin wrote:
>> max at bruningsystems.com ?????:
>>> Hi,
>>> Victor Latushkin wrote:
>>>>
>>> I have decided to file an RFE so that zdb with the -R option will
>>> allow one to decompress data before dumping it. I have had this
>>> implemented for several months now, and was told that a way to get
it
>>> into opensolaris was to file an RFE. However, when I go to file the
>>> RFE, after typing in the information and hitting "send",
I am
>>> getting: >
>>>
>>> Not Found
>>>
>>> The requested URL /bug/os was not found on this server.
>>>
>>>
------------------------------------------------------------------------
>>>
>>> Apache/2.0.58 (Unix) mod_ssl/2.0.58 OpenSSL/0.9.8a DAV/2
proxy_html/2.5
>>> mod_jk/1.2.15 Server at www.opensolaris.org Port 80
>>>
>>> Any ideas?
>>
> So you are unable to submit a bug?
>
> When did this happen (date/time)?
>
> I will check the logs.
>
> Derek
>
I have decided not to file an RFE, as Victor points out that it was 
already filed.
(I searched for keyword zfs, and decompress in text.  Victor suggested I try
zfs and decompress both in text).  However, this error occurred this morning
(last night, California time around 11:45pm, October 30).
thanks,
max