----- Original Message ----- > From: "Daryl Herzmann" <akrh...@iastate.edu> > To: "Red Hat Enterprise Linux 6 (Santiago) discussion mailing-list" > <rhelv6-list@redhat.com> > Sent: Wednesday, August 15, 2012 7:32:15 AM > Subject: Re: [rhelv6-list] Nasty bug with writing to resyncing RAID-5 Array > > On Sun, Jun 24, 2012 at 12:48 PM, Stephen John Smoogen > <smo...@gmail.com> wrote: > > On 23 June 2012 11:04, Daryl Herzmann <akrh...@iastate.edu> wrote: > >> On Fri, Jun 22, 2012 at 4:03 PM, Stephen John Smoogen > >> <smo...@gmail.com> wrote: > >>> On 22 June 2012 14:10, daryl herzmann <akrh...@iastate.edu> > >>> wrote: > >>>> Howdy, > >>>> > >>>> The RHEL6.3 release notes have a curious entry: > >>>> > >>>> http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/6.3_Technical_Notes/kernel_issues.html > >>>> > >>>> kernel component > >>>> > >>>> Due to a race condition, in certain cases, writes to RAID4/5/6 > >>>> while the > >>>> array is reconstructing could hang the system > >>>> > >>>> Wow, I am reproducing it frequently here. Simply have a RAID-5 > >>>> software > >>>> array and do some write IO to it, eventually things start > >>>> hanging and the > >>>> power button needs to be pressed. > >>>> > >>>> Oh man. > >>> > >>> Well the race condition they are mentioning should only happen > >>> when > >>> the RAID array is reconstructing. This sounds like a different > >>> bug/problem. What kind of disks, type of RAID etc. > >> > >> Thanks for the response. I am not sure of the difference between > >> 'reconstructing' and 'resyncing' and/or 'syncing'. The > >> reproducing > >> case was quite easy for me. > >> > >> 1. Create a software raid5 > >> 2. Immediately then create a filesystem on this raid5, while init > >> sync underway > >> 3. IO to the RAID device eventually stops, even for the software > >> raid5 sync > > > > Ok reconstructing is where the initial RAID drives pair up with > > each > > other. Resyncing I believe is where a RAID which has been created > > is > > putting the data across its raid. Basic cat /proc/mdstat.. if there > > is > > a line ====> then you are reconstructing the disk array. In the > > example you give above, the disks would be reconstructing > > > > So the next thing to do is why you are able to trigger it > > constantly. > > That may be due to > > CPU Type: > > RAM Amount: > > Disk controllers: > > DIsk types (SATA, SAS, SCSI, PATA): > > RAID type: > > RAID layout (same controller, different controller, etc): > > I don't seem to have much issue reproducing, I just had another > machine do it this morning. Nehalem processor, 12 GB ram, Dell > PowerEdge T400, Perc 6i controller, software raid 5, Seagate 2 TB > Barracuda drives... > > Does anybody have the bugzilla ticket associated with this or perhaps > a knowledge base article on it? > > daryl >
I would like to know too. I have not seen this issue yet but I do have some large RAID6 arrays. David. _______________________________________________ rhelv6-list mailing list rhelv6-list@redhat.com https://www.redhat.com/mailman/listinfo/rhelv6-list
