When a file is renamed from multiple mount points, there is a possibility to lose the file. This is noticed when the mv command internally processes it as an unlink operation after a rename, when the source and destination paths are hardlinks of each other. This issue occurs in the coreutil packages in various Linux distributions.
For example, if there are parallel rename operation (mv a b) and (mv b a) where a and b are hardlinks to the same file, because of the above mentioned behaviour of mv, unlink (a) and unlink (b) would be issued from both instances of mv. This results in losing both the links a and b and hence the file.
Description of problem:
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DATA LOSS - rename from multiple mount ends in data loss(files are deleted), rename from one mount + rebalance + lookup also ends in data loss
Version-Release number of selected component (if applicable):
=============================================================
3.6.0.28-1.el6rhs.x86_64
How reproducible:
=================
always
Steps to Reproduce:
===================
1. created Ditributed volume having 4 bricks.
2. created 100 files on mount - mb{1..100}-1
case 1:- rename from multiple mount :-
3. create link file for each file. eg. for file 'a', create link 'b' and then from one mount execute'mv a b' and from another mount execute 'mv b a' at same time. keep sending lookup from another mount.
4. many files are missing from mount as well as backend
*{3,5,17,18,20,15,31,36,41,52,58,62,65,74,76,77,85,87,95}-1 are missing
case 2: - rename from one mount + rebalance + lookup
5. now run the rename from one mount as below
for file 'a', create link 'b' and then from one mount execute'mv a b'
at same time add-brick and start rebalance and keep sending lookup from another mount
6. many files are missing from mount as well as bricks
*{46,64,97}-1 are missing
Actual results:
===============
data loss - files are missing from mount and brick
Document URL:
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Describe the issue:
Suggestions for improvement:
Additional information:
Description of problem:
Version-Release number of selected component (if applicable):
How reproducible:
Steps to Reproduce:
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Actual results:
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Additional info:
Bz 1166570, on which this bug depends on, has been resolved in RHEL-7.2. Since we shipped rhgs-3.1.3 on RHEL-7.2, this bug should not be present on rhel-3.1.3
Status: ASSIGNED → MODIFIED
Fixed In Version: coreutils-8.22-13.el7
Verified this bug on glusterfs version 3.7.9-12.el7rhgs.x86_64.
Here are the steps that were performed,
1. Created a ditributed replica volume and started it.
2. FUSE and nfs mounted the volume on two different clients.
3. Created files on the mount point.
case 1:- rename from multiple mounts:
4. Created link file for each file. eg. for file 'a', create link 'b' and then from one mount executed 'mv a b' and from another mount executed 'mv b a' at same time. Also, sending continuous lookups from one mount.
5. Checked the files count after some time. File count remains same and No data loss was seen.
case 2: - rename from one mount + rebalance + lookup
6. Renamed files from one mount as below
for file 'a', create link 'b' and then from one mount execute'mv a b'
at same time add-brick and started rebalance and continuous lookups from another mount
7. Checked the file count after rebalance. File count remains same and No data loss was seen.
Hence, moving this bug to Verified.
Comment 12Nithya Balachandran
2016-09-16 06:13:50 UTC
Thanks Prasad.
I am closing this BZ based on comment#11
Description of problem: ======================= DATA LOSS - rename from multiple mount ends in data loss(files are deleted), rename from one mount + rebalance + lookup also ends in data loss Version-Release number of selected component (if applicable): ============================================================= 3.6.0.28-1.el6rhs.x86_64 How reproducible: ================= always Steps to Reproduce: =================== 1. created Ditributed volume having 4 bricks. 2. created 100 files on mount - mb{1..100}-1 case 1:- rename from multiple mount :- 3. create link file for each file. eg. for file 'a', create link 'b' and then from one mount execute'mv a b' and from another mount execute 'mv b a' at same time. keep sending lookup from another mount. 4. many files are missing from mount as well as backend *{3,5,17,18,20,15,31,36,41,52,58,62,65,74,76,77,85,87,95}-1 are missing case 2: - rename from one mount + rebalance + lookup 5. now run the rename from one mount as below for file 'a', create link 'b' and then from one mount execute'mv a b' at same time add-brick and start rebalance and keep sending lookup from another mount 6. many files are missing from mount as well as bricks *{46,64,97}-1 are missing Actual results: =============== data loss - files are missing from mount and brick Document URL: Section Number and Name: Describe the issue: Suggestions for improvement: Additional information: Description of problem: Version-Release number of selected component (if applicable): How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info: