Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

For bugs related to Red Hat Enterprise Linux 3 product line. The current stable release is 3.9. For Red Hat Enterprise Linux 6 and above, please visit Red Hat JIRA https://issues.redhat.com/secure/CreateIssue!default.jspa?pid=12332745 to report new issues.

Bug 121716 (IT_52396)

Summary:	Raw device I/O transfer size limited to 32KB.
Product:	Red Hat Enterprise Linux 3	Reporter:	Keith Kauffman <kkauffma>
Component:	kernel	Assignee:	Stephen Tweedie <sct>
Status:	CLOSED ERRATA	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	3.0	CC:	coughlan, nobody+wcheng, petrides, riel, sabdelg, tao, trondeg
Target Milestone:	---
Target Release:	---
Hardware:	i686
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2005-05-18 13:27:22 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	131391
Bug Blocks:

Description Keith Kauffman 2004-04-26 18:18:37 UTC

Description of problem:
After modifying the Qlogic HBA driver module to support large bock 
transfers, statistics were gathered that suggest to maximum transfer 
size was 32KB.

Version-Release number of selected component (if applicable):
kernel-smp-2.4.21-9.0.3.EL

How reproducible:
Always

Steps to Reproduce:
1. Modify the Qlogic HBA driver (versions 6.06.65, 6.06.00b11, 
6.06.10, and 7.00.00b23) to support large block transfers (qla2x00.h -
 SG_SEGMENTS defined as SG_ALL, max_sectors defined as 8192).
2. Compile and install driver.
   $make all install
3. Reload driver module
   $modprobe -r qla2300
   $modprobe -v qla2300
4. Use dd to issue reads to /dev/raw/raw1 (raw device bound 
to /dev/sdb - LSI RAID disk).
   $dd if=/dev/raw/raw1 of=/dev/null bs=512K count=1024
   $dd if=/dev/raw/raw1 of=/dev/null bs=512K count=1024
  
Actual results:
Maximum transfer size: 32KB

Expected results:
Maximum transfer size: 512KB

Additional info:

Comment 1 Keith Kauffman 2004-04-30 16:41:22 UTC

Kernel version 2.4.21-14 (from the beta channel) does not appear to 
resolve this issue with respect to raw devices.  The transfer size is 
still limited to 32K.  Block device transfer size was found to be 
~128K.

Command executed:
dd if=/dev/raw/raw1 of=/dev/null bs=512k count=1000
(/dev/raw/raw1 bound to /dev/sda - LSI RAID disk)

(The assumption was made that 2.4.21-14 contains the same fixes as 
2.4.21-12 referenced in bug 104633.)

Red Hat 7.3 kernel version 2.4.20-28.7 does not exhibit this 
behavior.  The transfer size reported was 512K.

Comment 7 Stephen Tweedie 2005-03-03 14:57:32 UTC

A patch to allow raw IOs ("superbh" IOs) larger than 32k has been committed for
the U5 kernel.

Comment 8 Ernie Petrides 2005-03-04 03:12:38 UTC

The fix referred to in comment #7 was committed to the RHEL3 U5
patch pool on 23-Feb-2005 (in kernel version 2.4.21-28.EL).

Comment 9 Tim Powers 2005-05-18 13:27:22 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2005-294.html