Pasi Kärkkäinen wrote:
On Fri, Mar 26, 2010 at 11:14:18AM -0700, Benjamin Franz wrote:
Robert Heller wrote:
I suspect that this is a simular case to what I did: I have a server with 4 drives. I have several (small) RAID1 partitions (/boot, /, /usr, /var, etc.) with 4 mirrors and one large RAID5 with three partitions and a hot spare (a LVM volumn group, containing /home and some other partitions). I would guess that the admin with the "8-way RAID1 for the OS" probably also has a 6 or 8 disk RAID5 or RAID6 for the bulk of the disks
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..
A hardware controller can fail in ways that kill the kernel too.