Bug 44327 - cp command produces different file on RAID 5 IDE disks
Summary: cp command produces different file on RAID 5 IDE disks
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: kernel   
(Show other bugs)
Version: 7.1
Hardware: i686 Linux
Target Milestone: ---
Assignee: Arjan van de Ven
QA Contact: Aaron Brown
Depends On:
TreeView+ depends on / blocked
Reported: 2001-06-12 21:44 UTC by Need Real Name
Modified: 2007-04-18 16:33 UTC (History)
0 users

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2003-06-06 13:19:55 UTC
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

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Description Need Real Name 2001-06-12 21:44:07 UTC
From Bugzilla Helper:
User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows NT 4.0)

Description of problem:
I installed the RH7.1 server system on a PC containing 4 IBM UDMA disks. 
If those disks are configured to RAID 5, the resultant file of the cp (and 
dd) command is DIFFERENT from the original file! However, on the same 
hardware, the cp (and dd) command produces the SAME target file as the 
original if I DO NOT use RAID array.

How reproducible:

Steps to Reproduce:
1.cp dx100.tar dx100.tar1 (while dx100.tar is of 650MB size)
2.cmp dx100.tar dx100.tar1
3.cp dx100.tar dx100.tar2 (just repeat the procedure)
4.cmp dx100.tar dx100.tar2 

Actual Results:  the cmp result (of step 2):"dx100.tar and dx100.tar1 
differ: char 9359357 line 33367"

the cmp result (of step 4) "dx100.tar dx100.tar2 differ: char 106258429 
line 1321617"

Expected Results:  the cmp should returns 0 (not 1) because both 
dx100.tar1 and dx100.tar2 are the direct copy of dx100.tar.

Additional info:

The hardware is as follows:
Motherboard: Epox (EP-D3VA)
CPU: PIII 866MHz x 2 (dual cpu)
RAM: 512MB
Hard disks: (4 x) IBM UDMA 41.0GB

I also installed RH7.1 server to the same PC without configuring the hard 
drives to RAID array. The cp command produced the correct result.

Furthermore, I have 2 other servers using SCSI RAID5 disks (under RedHat 
6.2 and RedHat 7.0). The cp command is OK.

I also have a server using IDE RAID1 under RedHat 7.0. The cp command 
works OK.

Comment 1 Bernhard Rosenkraenzer 2001-06-27 15:27:27 UTC
cp and dd don't make a difference between raid and non-raid devices. I tend to 
believe this is a raid driver bug.

Comment 2 Arjan van de Ven 2001-06-27 16:37:20 UTC
I assume this is linux softwareraid.

Could you try running with "ide=nodma" as commandline option to rule out
IDE DMA corruption ?

Comment 3 Need Real Name 2001-06-29 07:19:45 UTC
After further test, I believe that the problem might be in the driver for the 
onboard HTP370 (IDE adaptor) driver. 

I have been using a mother board (EPOX D3VA) consisting 2 conventional UDMA66 
channels and further 2 UDMA100 channels based on a HTP370 (High Point 370) 
chipset. Under Redhat 7.1, the disks on the conventional UDMA66 channels 
are /dev/hda, /dev/hdb, ..., /dev/hdd and the disks on the HTP channels 
are /dev/hde, ..., /dev/hdh. 

Using Redhat 7.1 software RAID 5 on the conventional UDMA66 channels 
(/dev/hda, ..., /dev/hde), the result is OK and there is NO data corruption! 
This indicates that the software for the RAID 5 in Redhat 7.1 is OK.

However, I got the reported data corruption problem when connecting the SAME 
disks, the SAME RAID 5 configuration (just changing /dev/hda to /dev/hde, etc 
in the /etc/raidtab) to the HTP channels. Furthermore, when I put the disks to 
the UDMA66 channels (using /dev/hda, etc.) together with the reported corrupted 
data on the disks and run the cmp command, the cmp magically returns 0 (ie. no 
data corruption!) 

Further tests show NO data corruption on individual disk when connected to the 
HTP channels (ie, not running RAID5). Therefore, I now suppect that the problem 
is caused by the combination of RAID5 and HTP370 driver.

Comment 4 Need Real Name 2001-06-29 15:47:44 UTC
Sorry, I already took that machine apart and replaced with a different mother 
board (SuperMicro 370DLE) and using a 3ware (http://www.3ware.com) Escalade 
6800 raid card. However, I still choose to use the software raid as it offers 
better performance than the hardware RAID5. Because the 3ware uses SCSI 
interface on the UDMA disk, the software RAID5 (on scsi disks) does suffer data 

I will try to use ide=nodma next time when I setup the Epox D3VA hardware and 
let you know the result.

Comment 5 Alan Cox 2003-06-06 13:19:55 UTC
Closing: Appears to be the now worked around old VIA chipset hardware problem

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