Re: Hardware RAID setup
Bill Moseley said:
> Then either reboot and alt-3, or install and use the 3dm (or tw_cli)
> utility and select verify which will mirror the disk and enable RAID 1.
> Sound right?
I've only used the 6400 and 6800 3ware cards but never remember
having to run a 'verify'. Maybe the cards I had didn't have the option.
> I think I asked this before, but if the array looks like a single drive
> can you use hdparm on the individual drives?
doubtful, the OS is not aware of the individual disks in any way.
> Do you know what that driver does for the kernel? Again, I kind of
> imagined that with hardware raid the OS would just see a single drive. Is
> that driver needed for using RAID at all, or does it just provide a way
> for user programs like 3dm and tw_cli to access special features of the
> hardware (like displaying device status and starting a verify operation)?
the driver makes it so the OS can see the controller & raid virtual
disk. without the driver the OS will not be able to use the controller
and thus the array. the driver also allows the 3dm software to communicate
directly with the array(check the array, remove disks, add disks, change
cache settings etc).
be sure to test, on my systems if a disk failed the system would kernel
panic. Maybe the 7000 controllers are better, but the 6800 series for
sure did not do a sufficient job of masking a disk failure, the kernel
would detect a sudden burst of bad sectors and reiserfs would puke
immediately killing the system. And this was in a 6-disk RAID 10 setup,
the controller should of done a better job of masking the disk failure
since there was another complete mirror copy on the 2nd disk of the raid
1 set. I have simulated hardware failures on software raid (again with
reiserfs), with no trouble, the filesystem wasn't even aware the disk
failed(which is how it should be).
and I did have a LOT of disk failures, probably 12-13 failures accross
a period of 1 and a half years on 4 different systems running 3ware
cards, most of the failures were IBM 75GXP(~85%) though there was
about 3 drives that failed after I switched to maxtor drives.