The subject of the mail should be "raid 10 or 0+1" I believe :) According to acnc.com: http://www.acnc.com/04_01_10.html "RAID 10 is implemented as a striped array whose segments are RAID 1 arrays " http://www.acnc.com/04_01_0_1.html "RAID 0+1 is implemented as a mirrored array whose segments are RAID 0 arrays" If a drive were to fail in a RAID0+1, what you are left with is essentially one RAID0 array. You want to use RAID10 if you need high performance and very good fault tolerance. The disadvantage is that you end up with half of the available raw space as useable. I've never seen nor tried a "/" file system on RAID10 or RAID0+1. What I usually hear recommended is /boot and or / on RAID1 and then if you need better performance for a database or other application, then create a /data partition or something of the sort on a separate RAID10 array that is on different disk spindles. Here is our configuration: /: RAID1 /backup: RAID0 disk backup staging area /data: LVM on a 56 SCSI disk SW RAID10 array HTH, Andy. > -----Original Message----- > From: linux-raid-owner@xxxxxxxxxxxxxxx > [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Andre Noll > Sent: Sunday, April 24, 2005 9:54 AM > To: linux-raid@xxxxxxxxxxxxxxx > Subject: Re: raid 10 or 1+0 ? > > On Sat, 23 Apr 2005 12:21:17 -0400 you wrote in > local.lists.linux-raid: > > > Maybe we need some success stories for RAID10 and RAID1+0 > mounted on "/". > > I have such a setup up and running for quite some time now: > > cat /proc/mdstat > Personalities : [raid0] [raid1] > md3 : active raid0 md1[0] md2[1] > 156247808 blocks 64k chunks > > md2 : active raid1 hda2[0] hdk2[1] > 78123968 blocks [2/2] [UU] > > md1 : active raid1 hdc2[0] hdg2[1] > 78123968 blocks [2/2] [UU] > > md0 : active raid1 hdc1[2] hda1[3] hdk1[1] hdg1[0] > 49280 blocks [4/4] [UUUU] > > My roottfs is on a lv. The corresponding vg is made from md3. > > This works if you do not rely on the kernel to assemble your > array but use an initrd to achieve this. > > Just use something like this in your linuxrc, right after > creating the device nodes (if you use udev): > > if test -e /proc/mdstat; then > log "scanning for multi disk devices" > echo "DEVICE /dev/hd[a-z] /dev/sd[a-z] > /dev/md[0-9]" > /etc/mdadm.conf > mdadm --examine --scan --config=/etc/mdadm.conf \ > >> /etc/mdadm.conf > mdadm --assemble --scan > fi > > if test -c /dev/mapper/control; then > log "setting up lvm" > vgscan --mknodes > vgchange -a y > fi > > > BTW, you should definitively use striped mirrors rather than > mirrored stripes. > > However, note that you can not boot from a striped mirror. > That is, you need a tiny partition, preferably at the > beginning of your discs, to store the kernel image and the > initrd, but not the rootfs. You can make it a raid1 over all > disks, like my md0 above, and use lilo to write a mbr to > _all_ discs. That way you can shuffle around your discs and > your system will still boot. > > More details on request ;) > Andre > -- > Andre Noll, http://www.mathematik.tu-darmstadt.de/~noll > > - > To unsubscribe from this list: send the line "unsubscribe > linux-raid" in the body of a message to > majordomo@xxxxxxxxxxxxxxx More majordomo info at > http://vger.kernel.org/majordomo-info.html > Confidentiality Notice: This e-mail message including attachments, if any, is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message. If you are the intended recipient, but do not wish to receive communications through this medium, please so advise the sender immediately. - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
