Re: [Iometer-devel] [Iometer-user] A possible solution to 4K disksectoralignmentissue.

[Ming Z. <mi...@el...>]

Hi ALL

I checked old list archive about these 2 ioctl, BLKSSZGET and BLKBSZGET.
I feel we should use BLKSSZGET here. 

this value is only used for alignment check and thus we should allow
tester to test 512b request no matter what. 

iometer as a tool should provide a mechanism here while not enforcing a
policy. if it is legal to write 23 bytes each time to a file even the
file system has 4KB block size, then why we should prevent testers from
doing that? 


Ming




On Tue, 2006-09-19 at 17:12 -0400, Ming Zhang wrote:
> Hi Liang
> 
> Thanks a lot. I will read kernel code again to further confirm this and
> commit the change if everything is ok.
> 
> Ming
> 
> 
> On Tue, 2006-09-19 at 11:21 -0700, Liang Yang wrote:
> > Hi Ming,
> > 
> > I tested on sas, raid and lvm and it seems IOMeter works properly.
> > 
> > Liang
> > 
> > ----- Original Message ----- 
> > From: "Ming Zhang" <mi...@el...>
> > To: "Liang Yang" <mul...@ho...>
> > Cc: "iometer-devel-list" <iom...@li...>
> > Sent: Saturday, September 16, 2006 5:01 AM
> > Subject: Re: [Iometer-user] A possible solution to 4K 
> > disksectoralignmentissue.
> > 
> > 
> > > sas, raid, lvm over raid or sas are good enough. thanks!
> > >
> > > Ming
> > >
> > > On Fri, 2006-09-15 at 18:49 -0700, Liang Yang wrote:
> > >> I only have SAS/SATA drives, no scsi drives. I will run raw drive and 
> > >> RAID
> > >> testing on them and let you know the result.
> > >>
> > >> Liang
> > >>
> > >> ----- Original Message ----- 
> > >> From: "Ming Zhang" <mi...@el...>
> > >> To: "Liang Yang" <mul...@ho...>
> > >> Cc: "iometer-devel-list" <iom...@li...>
> > >> Sent: Friday, September 15, 2006 5:54 PM
> > >> Subject: Re: [Iometer-user] A possible solution to 4K disk
> > >> sectoralignmentissue.
> > >>
> > >>
> > >> > if possible, could u run it against file system, raw scsi/ide disk, md,
> > >> > lvm and see if all as desired? if so, i will do the change. thanks!
> > >> >
> > >> > Ming
> > >> >
> > >> > On Fri, 2006-09-15 at 17:04 -0700, Liang Yang wrote:
> > >> >> Ming,
> > >> >>
> > >> >> After chaning BLKBSZGET to BLKSSZGET, I re-compiled the Dynamo on 
> > >> >> RedHat
> > >> >> Enterprise AS 4.4 (kernel version 2.6.9) and the IOMeter (RC3) works
> > >> >> properly with 512B access specification now.
> > >> >>
> > >> >> Just FYI,
> > >> >>
> > >> >> Liang
> > >> >>
> > >> >> ----- Original Message ----- 
> > >> >> From: "Ming Zhang" <mi...@el...>
> > >> >> To: "Liang Yang" <mul...@ho...>
> > >> >> Cc: <iom...@li...>
> > >> >> Sent: Thursday, September 14, 2006 7:24 PM
> > >> >> Subject: Re: [Iometer-user] A possible solution to 4K disk sector
> > >> >> alignmentissue.
> > >> >>
> > >> >>
> > >> >> > yes, that comment is about this issue. i will try to find out the 
> > >> >> > right
> > >> >> > one. thanks for reminding.
> > >> >> >
> > >> >> > Ming
> > >> >> >
> > >> >> > On Thu, 2006-09-14 at 17:25 -0700, Liang Yang wrote:
> > >> >> >> Hi,
> > >> >> >>
> > >> >> >> Just got the answer from a friend about disk sector alignment issue
> > >> >> >> when
> > >> >> >> running IOMeter in Linux, he suggested changing BLKBSZGET in
> > >> >> >> IOTargetDisk.cpp to BLKSSZGET may solve the disk sector alignment
> > >> >> >> problem
> > >> >> >> in
> > >> >> >> Linux.
> > >> >> >>
> > >> >> >> I noticed there are some comments there and maybe that is not 
> > >> >> >> correct.
> > >> >> >>
> > >> >> >> "Use BLKBSZGET here as opposed to BLKSSZGET.  BLKSSZGET returns the
> > >> >> >> true
> > >> >> >> sector size of the physical disk which should be what we want.
> > >> >> >> However,
> > >> >> >> Linux will always use the potential cluster size of the file system
> > >> >> >> even
> > >> >> >> for
> > >> >> >> raw devices with no file system.  So we use BLKBSZGET which returns
> > >> >> >> the
> > >> >> >> (potential) file system cluster size."
> > >> >> >>
> > >> >> >> Liang
> > >> >> >>
> > >> >> >>
> > >> >> >> -------------------------------------------------------------------------
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> > >> >> >> Geronimo
> > >> >> >> http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
> > >> >> >> _______________________________________________
> > >> >> >> Iometer-user mailing list
> > >> >> >> Iom...@li...
> > >> >> >> https://lists.sourceforge.net/lists/listinfo/iometer-user
> > >> >> >
> > >> >> >
> > >> >>
> > >> >
> > >> >
> > >>
> > >
> > > 
> > 
>