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<p class="MsoNormal">Developers,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have system with configuration as <o:p></o:p></p>
<p class="MsoNormal">RAM : 4G<o:p></o:p></p>
<p class="MsoNormal">SWAP: 2G<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On this system I had created an XFS file system of size 250 GB, I am using xfs_db utility to get file mapping( file name and inode number ) information using the daddr & corresponding File system block number. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/dev/sdd1 : 250G filesystem, 13% (29 G) full, aprox 3.5 million files<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Steps executed in getting this information is as below :<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">test# xfs_db -i -c "convert daddr 6612146 fsb" /dev/sdd1<o:p></o:p></p>
<p class="MsoNormal">0xc9c96 (826518)<o:p></o:p></p>
<p class="MsoNormal">test:~ # xfs_db -i -c "blockget -n -b 826518" /dev/sdd1<o:p></o:p></p>
<p class="MsoNormal">xfs_db: out of memory<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Utility (xfs_db ) is giving OOM in extracting block information using “blockget” and in some cases it gives OOM when subcommand “ncheck”of xfs_db. It is mentioned in the manuals itself that ncheck is memory consuming command. When we
analysed the command memory map of ncheck using “pmap” most of the memory is consumed in heap. It’s not utilized by cache memory.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Whether xfs_db stores information of all the blocks upto the requested block or it maintains its internal structure. When checking the xfs_db codethen found function call like (push_cur() etc ) whether it is maintaining its own command
execution stack. <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Instead of accessing the device itself can we read the metadump file to get the required information of file mapping with file system block number. Its binary file but is there any utility which reads the metadump file itself instead of
file system image. As it is easier to read the metadump file instead of go towards disk access itself. There is file obfuscation in the file name for 4 characters
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Whether reading metadump file for getting file mapping with file system block number still consumes same amount of memory or this will not works.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Please provide some reference to either eliminate the OOM (in blockget and ncheck) or any other way either related to accessing metadump file in getting the mapping (fsbno to file name or inode number ). As currently finding out the cause
of this memory consumption from the source itself whether optimization in finding this mapping information is possible or not <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">On finding out solution over the OOM I found reference of xfs_db 64 but there is no 64 bit version of utility available in xfs website either there will be some configuration option or it becomes obsolete.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks & Best Regards <o:p></o:p></p>
<p class="MsoNormal">Anshul Kundra <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
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