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Bug 465261

Summary: [5.3][RFE] Copying of Vmcore Not Sparse Awareness
Product: Red Hat Enterprise Linux 5 Reporter: Qian Cai <qcai>
Component: kexec-toolsAssignee: Neil Horman <nhorman>
Status: CLOSED NOTABUG QA Contact: Martin Jenner <mjenner>
Severity: low Docs Contact:
Priority: low    
Version: 5.2CC: varekova
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2008-10-02 14:44:57 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description Qian Cai 2008-10-02 13:50:42 UTC 
Description of problem:
In Kdump initramfs, it uses busybox version of cp to save the vmcore to disk. However, it could not handle sparse file. If we could something similar to GNU version of cp's --sparse option, it could be a huge time and disk space saving. For example, in a SGI Altix IA64 machine,

it only take 3 minutes and 1.6G disk space for a 123G vmcore using GNU cp.

time cp --sparse=always /proc/vmcore vmcore.bcp.sp
[root@altix3 ~]# time cp --sparse=always /proc/vmcore vmcore.bcp.sp

real	3m1.078s
user	0m54.367s
sys	1m43.683s

[root@altix3 ~]# ls -lh vmcore.bcp.sp
-r-------- 1 root root 123G Oct  2 09:45 vmcore.bcp.sp
[root@altix3 ~]# du -sh vmcore.bcp.sp 
1.6G	vmcore.bcp.sp

Alternative, we could make busybox to be sparse awareness. It appears Ivana is the RHEL busybox maintainer. Ivana, please let us know if there is a plan to add sparse file support in the near future.

Version-Release number of selected component (if applicable):
kexec-tools-1.102pre-21.el5

How reproducible:
always
Comment 1 Neil Horman 2008-10-02 14:44:57 UTC 
you can accomplish the same effect by specifying core_collector as makedumpfile -d 1