[SERVER-28170] How do you attempt a repair on a corrupted WiredTiger.wt file? Created: 02/Mar/17  Updated: 31/May/17  Resolved: 22/Mar/17

Status: Closed
Project: Core Server
Component/s: WiredTiger
Affects Version/s: 3.2.12
Fix Version/s: None

Type: Question Priority: Major - P3
Reporter: Ahmed Nasser Assignee: Kelsey Schubert
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

CentOS


Attachments: Text File 3.txt    
Participants:

 Description   

I would like to know how do you attemt to repair a corrupted WiredTiger.wt file. I am facing the checksum error in the attached log file. I have noticed similar issues that got fixed by repairing the WiredTiger.wt & WiredTiger.turtle files.

I have installed Wired Tiger tools with snappy as per the link: http://www.alexbevi.com/blog/2016/02/10/recovering-a-wiredtiger-collection-from-a-corrupt-mongodb-installation/

But I am not sure how to attempt to repair the checksum problem with WiredTiger.wt file itself.

I am not even sure this is meaningful, but I tried:

./wt -h ../ -v -C "extensions=[./ext/compressors/snappy/.libs/libwiredtiger_snappy.so]" -R salvage ../WiredTiger.wt

and got

[1488449862:382161][18727:0x7fdbd7239700], file:WiredTiger.wt, connection: read checksum error for 4096B block at offset 49152: block header checksum of 3921565147 doesn't match expected checksum of 3944682197
[1488449862:382221][18727:0x7fdbd7239700], file:WiredTiger.wt, connection: WiredTiger.wt: encountered an illegal file format or internal value
[1488449862:382238][18727:0x7fdbd7239700], file:WiredTiger.wt, connection: the process must exit and restart: WT_PANIC: WiredTiger library panic
lt-wt: WT_PANIC: WiredTiger library panic

How do I proceed with the repair attempt?



 Comments   
Comment by Kelsey Schubert [ 22/Mar/17 ]

Hi anasser,

Unfortunately, the script we use to attempt a repair isn't ready to be made publicly available. We have opened SERVER-19815, which tracks the work to make repair and recovery more robust. Please feel free to vote for SERVER-19815 and watch it for updates.

Kind regards,
Thomas

Comment by Ahmed Nasser [ 22/Mar/17 ]

Thank you @Thomas Schubert. My question was actually how do you do the repair attempt. I wanted to understand how you do it. If this is out of scope, then please feel free to close this ticket.

Comment by Kelsey Schubert [ 07/Mar/17 ]

Hi anasser,

If you can attach the unmodified WiredTiger.wt and WiredTiger.turtle, we'd be happy to make a repair attempt. Please note that the steps outlined in the link you've provided are not supported steps and modifying the underlying files in this way introduces a risk of further corruption.

Kind regards,
Thomas

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