Re: [Scst-devel] system crash

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 422-6466

This is basically correct. I would only add that using diskio you saves
some CPU overhead (all the data mem copied), but loosing caching and,
may be more important, readahead.

Vlad

Ming Zhang wrote:
> my understanding, not 100% right.
> 
> fileio is more flexible, it can export any regular file and block device
> as a scsi disk. so it can be very useful for stuff like lvm, evms, ...
> 
> fileio can introduce file system cache and lead to some performance gain
> and data inconsistency point; 
> 
> diskio is like a bridge, so less overhead to export a scsi disk compared
> with fileio. it should be useful as a FC-SCSI bridge.
> 
> for other device handlers, frankly i do not know. since i do not have
> such devices at all.
> 
> i only know a little about scsi_fileio.
> 
> Ming
> 
> 
> On Fri, 2006-05-19 at 11:36 -0500, Brad Johnson wrote:
> 
>>What are the advantages/disadvantages of using fileio instead of diskio?
>>Also, how does the raid device handler work?
>>
>>...Brad
>>
>>
>>On Fri, 2006-05-19 at 12:29 -0400, Ming Zhang wrote:
>>
>>>thx for the info. i never run diskio so i am not aware of its stability.
>>>maybe Vlad has better idea on this.
>>>
>>>Ming
>>>
>>>
>>>On Fri, 2006-05-19 at 11:25 -0500, Brad Johnson wrote:
>>>
>>>>I tried it again, this time using the fileio handler (I exported an
>>>>entire device /dev/sda1).
>>>>This time I did not have any problems. From the initiator system I ran
>>>>an entire bonnie disk I/O test run without failure.
>>>>
>>>>...Brad
>>>>
>>>>
>>>>On Thu, 2006-05-18 at 18:38 -0400, Ming Zhang wrote:
>>>>
>>>>>1) can u try latest code from scst cvs
>>>>>
>>>>>2) can u try to export it via scst_fileio module? see if oops in same
>>>>>place.
>>>>>
>>>>>ming
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>On Thu, 2006-05-18 at 17:20 -0500, Brad Johnson wrote:
>>>>>
>>>>>>The system running scst crashes when doing I/O to target from remote
>>>>>>system.
>>>>>>
>>>>>>Here is my setup:
>>>>>>My target system has 2 Intel Xeon processors (3.2 MHz) and 1 GB RAM.
>>>>>>It is running Linux 2.6.15.7.
>>>>>>It has scst-0.9.4 and qla2x00-target-26-0.9.3.8 installed.
>>>>>>It has a Qlogic 2312 HBA connected to a switch. This is my FC target
>>>>>>host. (My FC Initiator is another x86 system with a Qlogic HBA also
>>>>>>connected to the switch.)
>>>>>>For back-end devices it has an LSI FC949X HBA connected to a Hitachi
>>>>>>Fibre-channel drive.
>>>>>>
>>>>>>Here is my start script:
>>>>>>--------------------------------------------------------
>>>>>>modprobe -v qla2x00tgt
>>>>>>modprobe -v scst_disk
>>>>>>echo "add 2:0:3:0 0" >/proc/scsi_tgt/groups/Default/devices
>>>>>>echo "1" >/sys/class/scsi_host/host5/target_mode_enabled
>>>>>>--------------------------------------------------------
>>>>>>
>>>>>>In the script, 2:0:3:0 refers to my Hitachi drive, host5 refers to my
>>>>>>Qlogic target-mode port. Everything starts successfully (including
>>>>>>scsi_tgt module since it is a dependency of scst_disk).
>>>>>>
>>>>>>>From my initiator system I see the one drive I have exposed. I
>>>>>>successfully partition that drive and do mkfs. At this point everything
>>>>>>is still fine. I then mount the file system and copy a big file to it.
>>>>>>The copy seems to work fine but at some point shortly after that my
>>>>>>target system crashes. There is no oops output to the system log. So I
>>>>>>did it again with a remote kgdb attached. Here is the gdb output:
>>>>>>
>>>>>>
>>>>>>Program received signal SIGILL, Illegal instruction.
>>>>>>__free_pages (page=0xc190a22c, order=0) at mm/page_alloc.c:1055
>>>>>>1055            if (put_page_testzero(page)) {
>>>>>>(gdb) bt
>>>>>>#0  __free_pages (page=0xc190a22c, order=0) at mm/page_alloc.c:1055
>>>>>>#1  0xf8d61efd in scst_release_space (cmd=0xf40a4e58)
>>>>>>    at /root/mid-level/scst-0.9.4/src/scst_lib.c:1430
>>>>>>#2  0xf8d60b2a in scst_free_cmd (cmd=0xf40a4e58, check_retry=1)
>>>>>>    at /root/mid-level/scst-0.9.4/src/scst_lib.c:956
>>>>>>#3  0xf8d599ee in scst_finish_cmd (cmd=0xf40a4e58)
>>>>>>    at /root/mid-level/scst-0.9.4/src/scst_targ.c:2212
>>>>>>#4  0xf8d5a7df in __scst_process_active_cmd (cmd=0xf40a4e58,
>>>>>>    context=<value optimized out>, pflags=0xc046cfb8,
>>>>>>    left_locked=<value optimized out>)
>>>>>>    at /root/mid-level/scst-0.9.4/src/scst_targ.c:2461
>>>>>>#5  0xf8d5aa81 in scst_do_job_active (active_cmd_list=0xf8d756d0,
>>>>>>    pflags=0xc046cfb8, context=268435457)
>>>>>>    at /root/mid-level/scst-0.9.4/src/scst_targ.c:54
>>>>>>#6  0xf8d5af99 in scst_cmd_tasklet (p=<value optimized out>)
>>>>>>    at /root/mid-level/scst-0.9.4/src/scst_targ.c:2672
>>>>>>#7  0xc012d905 in tasklet_action (a=<value optimized out>)
>>>>>>    at kernel/softirq.c:267
>>>>>>#8  0xc012d552 in __do_softirq () at kernel/softirq.c:95
>>>>>>#9  0xc010619e in do_softirq () at arch/i386/kernel/irq.c:187
>>>>>>#10 0xc012d689 in irq_exit () at kernel/softirq.c:169
>>>>>>#11 0xc010604e in do_IRQ (regs=0xc1cf4f48) at arch/i386/kernel/irq.c:110
>>>>>>#12 0xc010499e in common_interrupt () at thread_info.h:91
>>>>>>#13 0xc1cf4000 in ?? ()
>>>>>>#14 0x00000000 in ?? ()
>>>>>>
>>>>>>
>>>>>>I can reproduce this easily every time. Let me know if you want any
>>>>>>further information about this.
>>>>>>
>>>>>>...Brad Johnson
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>-------------------------------------------------------
>>>>>>Using Tomcat but need to do more? Need to support web services, security?
>>>>>>Get stuff done quickly with pre-integrated technology to make your job easier
>>>>>>Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
>>>>>>http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
>>>>>>_______________________________________________
>>>>>>Scst-devel mailing list
>>>>>>Scs...@li...
>>>>>>https://lists.sourceforge.net/lists/listinfo/scst-devel
>>>>>
>>>>>
>>>>
>>>>
>>>>-------------------------------------------------------
>>>>Using Tomcat but need to do more? Need to support web services, security?
>>>>Get stuff done quickly with pre-integrated technology to make your job easier
>>>>Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
>>>>http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
>>>>_______________________________________________
>>>>Scst-devel mailing list
>>>>Scs...@li...
>>>>https://lists.sourceforge.net/lists/listinfo/scst-devel
>>>
>>>
>>
>>
>>-------------------------------------------------------
>>Using Tomcat but need to do more? Need to support web services, security?
>>Get stuff done quickly with pre-integrated technology to make your job easier
>>Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
>>http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
>>_______________________________________________
>>Scst-devel mailing list
>>Scs...@li...
>>https://lists.sourceforge.net/lists/listinfo/scst-devel
> 
> 
> 
> 
> -------------------------------------------------------
> Using Tomcat but need to do more? Need to support web services, security?
> Get stuff done quickly with pre-integrated technology to make your job easier
> Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
> _______________________________________________
> Scst-devel mailing list
> Scs...@li...
> https://lists.sourceforge.net/lists/listinfo/scst-devel
> 