At Sat, 27 Mar 2010 11:01:08 -0700 CentOS mailing list <centos@xxxxxxxxxx> wrote: > > Pasi Kärkkäinen wrote: > > On Fri, Mar 26, 2010 at 11:14:18AM -0700, Benjamin Franz wrote: > > > >> Yup. 8 way RAID1 for the OS, 8 way RAID6 for the data. I was hoping when > >> I setup the 8-way RAID1 for the OS that I would get really good read > >> speeds since md is supposed to stripe reads from RAID1, but in practice > >> the RAID6 completely kills it for read performance (~61 MB/sec from the > >> RAID1 partition vs ~200 MB/sec from the RAID6 partition). > >> > >> In a deeply ironic turn of events, one of the hard drives in that > >> machine died in a way that freaked the hardware controller driver out > >> and caused a kernel panic last week. > >> > >> > > > > I've also seen CentOS 5.3 (or 5.4, not sure) crash when a single sata hdd failed. > > The system was running mdadm RAID-1 mirror, so it shouldn't have been fatal event.. > > > > There was kernel oops on the console. too bad I didn't have time to capture it then. > > System was running AHCI SATA on Intel ICH9 controller, with mdadm software raid. > > > > So there's still need for hardware RAID controllers.. > > > > I'm not sure that is a good conclusion. The controller *is* a (3ware) > hardware RAID controller - but the drive failure caused the 3ware driver > to crash. That I wasn't using the controller in HW RAID mode may not be > a good indicator that all would have been well if I had been. There might be drive failure modes that put the drive controller into an 'odd' state. Still should not cause the software driver to crash -- I'd consider that a software bug. I've never heard of a SCSI HBA driver crashing. I might have encountered drive failure modes that would do things like hang the SCSI bus or otherwise confuse the SCSI HBA (eg causing it to fail to see *other* drives/devices). Since there is no SATA 'bus' (SATA drives are connected point-to-point 'star' fashion), a failed drive should not take the controller out, but I guess it depends on the signaling logic and what sort of logic gates are used for 'drive select'. Of course, a controller like the 3ware hardware RAID controller, configured in JOBD mode, probably looks like a SCSI HBA with bunch of disks on a single SCSI bus. > -- Robert Heller -- 978-544-6933 Deepwoods Software -- Download the Model Railroad System http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows heller@xxxxxxxxxxxx -- http://www.deepsoft.com/ModelRailroadSystem/
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