Ruslan Sivak wrote: > Toby Bluhm wrote: >> Ruslan Sivak wrote: >>> Feizhou wrote: >>>> Ruslan Sivak wrote: >>>>> Feizhou wrote: >>>>>> >>>>>>> I do have a SIL3114 chipset, and I think it's supposed to be >>>>>>> supported by device mapper. When I go to rescue mode, I see it >>>>>>> loading the driver for SIL3112, but nothing appears under >>>>>>> /dev/mapper except control. Are there instructions somewhere on >>>>>>> getting it to use my controller's raid? >>>>>> >>>>>> Your controller only has a bios chip. It has no raid processing >>>>>> capability at all. >>>>>> >>>>>> You need to use mdadm. anaconda should be able to let you create >>>>>> to mirrors and then create a third array that stripes those md >>>>>> devices, >>>>>> _______________________________________________ >>>>> Anaconda doesn't let me create a stripe raid set on top of a >>>>> mirror set. And it doesn't detect it when I do it manually. >>>>> Also the bios chip presents additional issues. I believe when I >>>>> don't have a raid array set up, it won't boot at all. When I have >>>>> it on raid10, I had trouble booting, and when I have it on >>>>> concatenation, everything works fine, until a drive is replaced. >>>>> At that point, i have to recreate the array, as concatenation is >>>>> not a fault tolerant set, and at this point I seem to lose all my >>>>> data. >>>> >>>> It won't boot at all without a raid array setup? That sounds really >>>> funny. >>>> >>> Actually I'm not 100% sure on this, but I think this is the case. I >>> believe the first time I set it up as a raid10, assuming that linux >>> will just ignore it. I installed centos by putting boot on a raid1, >>> and root on LVM over 2 raid1 sets. I had trouble getting it to boot. >>>>> Is there a way to get it to use the raid that's part of the bios >>>>> chip? >>>> >>>> Repeat after me. There is no raid that is part of the bios chip. It >>>> is just a simple table. >>> Yes, I know this is fakeraid, aka softraid, but I was hoping that >>> using the drivers would make it easier to support raid 10 then with >>> mdadm, which seems to be impossible to get to work with the >>> installer. I'm not even sure why the raid10 personality is not >>> loaded, as it seems to have been part of the mdadm since version 1.7. >>>>> Something about device mapper? >>>> >>>> >>>> You need the fake raid driver dmraid if you are going to set up >>>> stuff in the bios. What version of centos are you trying to >>>> install? libata in Centos 5 should support this without having to >>>> resort to the ide drivers. >>>> _________________________________ >>> I'm trying to install centos 5 - the latest. How would I go about >>> using dmraid and/or libata? The installer picks up the drives as >>> individual drives. There is a drive on the silicon image website, >>> but it's for RHEL4, and I couldn't get it to work. I'm open to >>> using md for raid, or even LVM, if it supports it. I just want to >>> be able to use raid10, as I can't trust raid5 anymore. >>> >> >> IIRC you had two out of four new disks die? So maybe it would be more >> accurate to say it's your hardware you don't trust. Raid5 is used >> without problems by ( I assume ) many, many people, myself included. >> You could have a raid10 and still lose the whole array if two disks >> that in the same mirror die at once. I guess no software in the world >> can really overcome bad hardware. That's why we do backups :) >> >> Anyway, perhaps excersizing /stressing the disks for a few days >> without error would make you feel more confident about the HDs. >> > > Actually, 2 disks did not die. Due to the fact that it was a new raid > 5 array (or for whatever reason), it was rebuilding the array. One of > the drives had a media error, and this caused the whole array to be lost. > This is exactly what this article warns about: > > http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt The article doesn't seem to mention the fact that if a disk in a mirror set dies and the remaining disk within the set starts to have data corruption problems, the mirror will be rebuilt from corrupted data. I don't know what you can do at this point, though. Perhaps make 2 separate mirrors and rsync them? You could keep copies of changes that way.