On Tue, 2010-12-14 at 14:27 +0100, Rik Theys wrote: > On Tue, 14 Dec 2010, Rik Theys wrote: > > > On Tue, 14 Dec 2010, Ben Hutchings wrote: > > > >> On Tue, 2010-12-14 at 13:24 +0100, Rik Theys wrote: > >>> This system _has_ > >>> a RAID controller and the disk is in a RAID1. Why would the filesystem > >>> switch > >>> to read-only mode? Is it because the RAID is too slow? If the RAID is too > >>> slow, > >>> this should just give a high iowait, but not make the file system > >>> read-only? > >> > >> The DMA mapping failure will be treated as an I/O error. Most > >> filesystems do not attempt to retry after an error. This has nothing to > >> do with the speed of the disk. > >> > >> Since you use RAID, the failure may only put a single disk in degraded > >> state, which will then be recoverable in the usual way. The error would > >> be hidden from the filesystem. > > > > The RAID in this system is a PERC H200, which should be a hardware RAID card. > > Can the mpt2sas driver see the physical disks that are part of the RAID? > > Looking at the kernel messages from bootup, the mpt2sas driver does seem to know > about the individual disks. OK. > There's also a failure message: > > [ 29.201218] mpt2sas0: failure at /build/buildd-linux-2.6_2.6.32-29-amd64-xcs37n/linux-2.6-2.6.32/debian/build/source_amd64_xen/drivers/scsi/mpt2sas/mpt2sas_scsih.c:3801/_scsih_add_device()! > > Is this message harmless? [...] According to the source code, it means that the driver found a device that is not an 'end device'. I think it's harmless. Ben. -- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse.
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