Mailinglist Archive: opensuse-bugs (3333 mails)

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https://bugzilla.novell.com/show_bug.cgi?id=699350

https://bugzilla.novell.com/show_bug.cgi?id=699350#c0


           Summary: Device Mapper Multipath is too slow at issuing
                    failback to large number of LUs under heavy load
    Classification: openSUSE
           Product: openSUSE 11.2
           Version: Final
          Platform: x86-64
        OS/Version: SLES 11
            Status: NEW
          Severity: Normal
          Priority: P5 - None
         Component: Kernel
        AssignedTo: kernel-maintainers@xxxxxxxxxxxxxxxxxxxxxx
        ReportedBy: sean.stewart@xxxxxxxxxx
         QAContact: qa@xxxxxxx
          Found By: ---
           Blocker: ---


User-Agent:       Mozilla/5.0 (Windows NT 5.1) AppleWebKit/534.24 (KHTML, like
Gecko) Chrome/11.0.696.71 Safari/534.24

After issuing a controller reboot while running I/O to 256 volumes with Device
Mapper, it can take up to 40 minutes for the failback process to complete and
all paths to be seen as expected. When running a reboot interval of 10 minutes
for an automated reboot test case, this almost inevitably leads to I/Os timing
out.


Reproducible: Always

Steps to Reproduce:
1. Map 255 volumes from an external storage array to a host running SLES 11 SP
1 and DMMP
2. Run I/O to these LUs using an I/O tool, to bog down the system
3. Reboot one of the controllers
Actual Results:  
The process of transferring and transferring back after the controller reboot
completes takes almost 40 minutes.  This can lead to I/Os timing out if
successive controller reboots take place, because DMMP can have no available
paths for some devices, even though the system has complete access to the
devices at the lower level.

Expected Results:  
DMMP should be quicker to discover the reinstated paths and failback to the
preferred paths.

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