On Mon, 2002-03-18 at 09:51, Sridhar Dhanapalan wrote: > I am thinking of purchasing a new computer with two hard drives of the same type > and size. I am interested in implementing a Linux software RAID0 (striping) > setup. I have a few questions on this. > > Firstly, can I still have a multi-boot configuration? For example, if I wanted > to allocate some space towards Windows and a few other OSs would I be able to > place the remainder into the Linux RAID0? In other words, must I fully dedicate > both devices to the RAID, or can I allocate what disc area I want in the RAID? I > assume that I would have to ensure that the disc space made available for the > RAID is identical on both drives.
Yes you can do both. What will be required of you when you create your md? devices are equally sized partitions. You can leave equal space at the end of both drives that you can use for other purposes, as long as the ( hda5+hdc5=md0 ) and ( hda6+hdc6=md1 ) and etc raid devices are there for your raid array. Here's an example setup with two IBM 30G Deskstars: [root@tamriel elx]# fdisk -l /dev/hde Disk /dev/hde: 255 heads, 63 sectors, 3737 cylinders Units = cylinders of 16065 * 512 bytes Device Boot Start End Blocks Id System /dev/hde1 * 1 3737 30017421 5 Extended /dev/hde5 1 3 24034+ fd Linux raid autodetect /dev/hde6 4 49 369463+ fd Linux raid autodetect /dev/hde7 50 65 128488+ fd Linux raid autodetect /dev/hde8 66 252 1502046 fd Linux raid autodetect /dev/hde9 253 3300 24483028+ fd Linux raid autodetect /dev/hde10 3301 3737 3510171 fd Linux raid autodetect [root@tamriel elx]# fdisk -l /dev/hdg Disk /dev/hdg: 255 heads, 63 sectors, 3737 cylinders Units = cylinders of 16065 * 512 bytes Device Boot Start End Blocks Id System /dev/hdg1 * 1 3737 30017421 5 Extended /dev/hdg5 1 3 24034+ fd Linux raid autodetect /dev/hdg6 4 49 369463+ fd Linux raid autodetect /dev/hdg7 50 65 128488+ fd Linux raid autodetect /dev/hdg8 66 252 1502046 fd Linux raid autodetect /dev/hdg9 253 3300 24483028+ fd Linux raid autodetect /dev/hdg10 3301 3737 3510171 fd Linux raid autodetect [root@tamriel elx]# I set this up manually with fdisk from the Mandrake LM81 cdrom command line, because for me it was easier to use a calculator and play with the block sizes to get the raid autodetect partitions set up. hde5+hdg5=md0, hde6+hdg6=md1, etc. Md0 is the only partition that is not RAID0; it's RAID1. It's also the /boot partition, because as far as I know, Lilo is not capable of booting from a RAID0 yet. So the /boot partition is mirrored instead, which IS supported under lilo. Plus it gives you some redundancy with your boot partition, which you need anyway. While my drives are completely occupied with RAID partitions, there's nothing stopping you from leaving an equal amount of space on either drive at the end and designating those partitions as vfats or whatever. The "hde" and "hdg" devices are coming from an HPT370 IDE chipset on the motherboard that supports drive striping under Windoze, but not under Linux. That's OK, because Linux software RAID is better anyway. The standard IDE interface is still there, and I've got a 4 gig drive on that; I just preferred to use the HPT370 IDE interface on this Abit motherboard for the primary boot devices. It clears the way to put experimental devices on the primary IDE interface. > Secondly, can Mandrake configure a RAID for me, for instance through Diskdrake? > If not, then can it install to a RAID? The LM81 install routines were very capable with regard to setting up the partitions and md devices. I was able to do everything I needed to do from a boot of the cdrom, even the Raid autodetect partitions; I just chose to do those from the command line. > Thirdly, I've read the Software-RAID HOWTO > (http://www.linuxdoc.org/HOWTO/Software-RAID-HOWTO.html); is this the best way > to go about things? The Boot-Root RAID HOWTO is the one you might want to check out, as it gets you as close as possible to booting from a RAID array. It explains what's required because of LILO limitations. > Fourthly, what should I do with my other IDE peripherals, namely a CD-RW and a > DVD drive? I don't want to spend any extra money on an IDE controller card > unless it is absolutely necessary, particularly since I don't use CDs often > (although I realise that speed is important when burning CDs). Is it alright to > leave them as primary and secondary slave devices (with the HDDs being the > primary/secondary masters)? The performance warnings in your documentation regarding slave devices are primarily with regard to you possibly striping a slave device (hard drive). This is a no no. The performance hit would be considerable. All your striped hard disk devices in your RAID array should be primary IDE devices. This only applies to devices in your RAID array. This doesn't necessarily apply to CDROM devices, since they are not involved during hard disk activity, and consequently are not involved in your filesystem IO. Therefore you should be able to leave these as slaves on their respective buses with no problem; in fact I've already done this. Note: The cleanest way to set up a winblows partition is to put it in on a seperate cheap 4 gig hard disk as an IDE slave device, thus giving you the freedom to use your two brand new drives completely in the RAID array. This is what I ended up doing. It won't affect your array performance. HTH, LX > TIA > > -- > Sridhar Dhanapalan > > "I actually think that Linux with the stuff that is going > on in 3D, desktops, etc., has a chance to become the first real > user-friendly UNIX." -- Linus Torvalds _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com
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