On Thu, Aug 16, 2012 at 1:08 PM, David C. Miller <[email protected]> wrote: > > > ----- Original Message ----- >> From: "Daryl Herzmann" <[email protected]> >> To: "Red Hat Enterprise Linux 6 (Santiago) discussion mailing-list" >> <[email protected]> >> 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 >> <[email protected]> wrote: >> > On 23 June 2012 11:04, Daryl Herzmann <[email protected]> wrote: >> >> On Fri, Jun 22, 2012 at 4:03 PM, Stephen John Smoogen >> >> <[email protected]> wrote: >> >>> On 22 June 2012 14:10, daryl herzmann <[email protected]> >> >>> 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.
The private bugzilla tracking this is: https://bugzilla.redhat.com/show_bug.cgi?id=828065 It appears the hope is to resolve this for the RHEL6.4 release. daryl _______________________________________________ rhelv6-list mailing list [email protected] https://www.redhat.com/mailman/listinfo/rhelv6-list
