Red Hat Bugzilla – Bug 168499
EXT3 filesystem writes are half slower than reads during backup and restore
Last modified: 2007-11-30 17:07:08 EST
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Description of problem:
I am using Redhat AS 3.0 (2.4.21-20.ELsmp) with EXT3 filesystems. The disks reside on a Fibre connected HP SAN storage. I am using HP Data Protector 5.0 for backups/restores.During backups, the average read speed is around 28 MB/s but during restores the write speeds drops down to 12-14MB/s.I have tried this on RAID 0+1 and RAID 5 storage but resutlts were the same.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1.Restore to RAID 0+1
2.Restore to RAID5
Actual Results: Results were the same. Write speed was around 12-14 MB/s MB/s.
Expected Results: Write speed should have been atleast 20-25 MB/s.
What is the HBA and driver? what model storage? any error messages in
The easiest way to proivide the needed info is to run sysreport and post the
To start with, it would be helpful to get some raw I/O performance numbers,
excluding the filesystem, etc. If you have a partition on the storage that you
can scratch, then run a simple test like "badblocks" and compare with "badblocks
-w". Use "vmstat 1" to monitor the performance. Post the reasults.
Please find the results of "sysreport" attached. Do I really need to run
tests on raw device because the issue here is the write performance on the
same filesystem while read performance is decent.
Please let me know how can I attach the output file of sysreport as it is
bzipped tar archive and bugzilla site is not allowing to attach it.
Created attachment 119027 [details]
Result of sysreport
I have attached the result of sysreport as requested.
Reverting to ASSIGNED state.
This bug is filed against RHEL 3, which is in maintenance phase.
During the maintenance phase, only security errata and select mission
critical bug fixes will be released for enterprise products. Since
this bug does not meet that criteria, it is now being closed.
For more information of the RHEL errata support policy, please visit:
If you feel this bug is indeed mission critical, please contact your
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information on how this bug is affecting you.