my sles10sp2 at 2.6.16.60-0.29-default doesn't have the /sys/block/.../holders but I've used major:minor device numbers from commands dmsetup ls and dmsetup deps to resolve such device relationships. A 'dmsetup ls' device number that isn't listed in 'dmsetup deps' device numbers is a top-level device. Example below: mproot-part1 (dev 253:3, a partition of mp device 253:2) isn't listed as a dependency of any device. Likewise each listed LVM volume isn't listed as a dependency of any device; example- rootvg-tmp 253:10 pz3vf129:~ # dmsetup ls rootvg-tmp (253, 10) mpboot (253, 0) rootvg-usr (253, 11) rootvg-var (253, 12) rootvg-opt.tivoli (253, 7) mproot (253, 2) rootvg-opt.tivoli.tsm (253, 8) rootvg-home (253, 5) mpboot-part1 (253, 1) rootvg-opt (253, 6) mproot-part2 (253, 4) rootvg-swap1 (253, 9) mproot-part1 (253, 3) pz3vf129:~ # dmsetup deps rootvg-tmp: 1 dependencies : (253, 4) mpboot: 8 dependencies : (8, 16) (8, 80) (8, 144) (8, 208) (8, 48) (8, 112) (8, 176) (8, 240) rootvg-usr: 1 dependencies : (253, 4) rootvg-var: 1 dependencies : (253, 4) rootvg-opt.tivoli: 1 dependencies : (253, 4) mproot: 8 dependencies : (8, 32) (8, 96) (8, 160) (8, 224) (8, 0) (8, 64) (8, 128) (8, 192) rootvg-opt.tivoli.tsm: 1 dependencies : (253, 4) rootvg-home: 1 dependencies : (253, 4) mpboot-part1: 1 dependencies : (253, 0) rootvg-opt: 1 dependencies : (253, 4) mproot-part2: 1 dependencies : (253, 2) rootvg-swap1: 1 dependencies : (253, 4) mproot-part1: 1 dependencies : (253, 2) > -----Original Message----- > From: dm-devel-bounces@xxxxxxxxxx [mailto:dm-devel-bounces@xxxxxxxxxx] > On Behalf Of Joel Becker > Sent: Monday, February 09, 2009 7:50 PM > To: dm-devel@xxxxxxxxxx > Cc: Sunil Mushran > Subject: Bug? Determining the holders of partitions shadowed > by dm-multipath. > > Folks, > I think this is a bug. > I I have a device with two paths, sda and sdb. The device is > partitioned into two partitions (sda1, sdb1) and (sda2, sdb2). The > multipath software will create me the devices mpath1, mpath1p1, and > mpath1p2. So far so good. > Now, I need to detect disks used by my software. There is a > signature on disks used by my software, so the basic algorithm is "for > each disk, check for the signature". But, as you know, multipath makes > this fun. You don't want to detect sda1 or sdb1, you want to detect > mpath1. This is true no matter how the devices are arranged (LVM > devices, kpartx of loopbacks, whatever it is). I'll use the term > "toplevel device" to describe a device that is not being used as part > of some other device. > So, how to determine toplevel devices? Well, > /sys/block/.../holders works for that, so I tried it. Sure enough, > /sys/block/sda/holders and /sys/block/sdb/holders point to mpath1. So > my software can reliably ignore sda and sdb. But when I look at > /sys/block/sda1/holders, it is empty. > The disk encompassing sda1 is held by another device. By > extension, sda1 is held. So I think it is a bug that > /sys/block/sda1/holders is empty. > Bug or not, what is the recommended way to determine that > /dev/sda1 should not be used, because you should be using > /dev/mpath/mpath1p1 (or whatever udev name it appears as)? > > Joel > > -- > > Life's Little Instruction Book #510 > > "Count your blessings." > > Joel Becker > Principal Software Developer > Oracle > E-mail: joel.becker@xxxxxxxxxx > Phone: (650) 506-8127 > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
