Re: [gentoo-user] md-device too small: where's my mistake?
Stefan G. Weichinger schrieb: md2 is the one that gives me headaches. AFAI understand it should be about 3TB in size, but it is only 774 GB # fdisk -l /dev/md2 Platte /dev/md2: 774.0 GByte, 774044975104 Byte I am surprised that noone seems to have advice for me. Is my mistake so obvious? Stefan
Re: [gentoo-user] md-device too small: where's my mistake?
Am Wednesday 22 October 2008 15:58:44 schrieb Stefan G. Weichinger: md2 is the one that gives me headaches. AFAI understand it should be about 3TB in size, but it is only 774 GB # fdisk -l /dev/md2 Platte /dev/md2: 774.0 GByte, 774044975104 Byte 2 Köpfe, 4 Sektoren/Spuren, 188975824 Zylinder Einheiten = Zylinder von 8 × 512 = 4096 Bytes Disk identifier: 0x Why? You cannot manage disks = ~2TB with fdisk (i.e., DOS partition tables), as they (or rather the on-disk-structure of DOS partition tables) have an inherent limitation in the maximum number of LBA48-blocks they can address. I'd presume that because of this inherent limitation, fdisk is reporting the wrong total size (2TB+774G+epsilon ~ 3TB; sounds like somewhere someone is doing a modulo operation, possibly), and completely off values for heads/sectors. Anyway, md-devices cannot be partitioned anyway (of course you can write a partition table on them, but the kernel won't use that to create md2-1,-2, etc.), so using fdisk is wrong. If you want to check the real size of the device, don't use fdisk, but rather use blockdev --getsize64 /dev/md2 which shows you the byte-count of the corresponding volume, and which I think will be 3TB, as you want it to be. If you want to subpartition large devices, use lvm(2), which does not have the 2TB limitation on size. Hope this helps! -- Heiko Wundram hackerkey://v4sw7CHJLSUY$hw5ln5pr7FOP$ck2ma9u7FL$w3DVWXm0l7GL$i65e6t3EMRSXb7ADORen5a26s5MSr2p-6.62/-6.56g5AORZ
Re: [gentoo-user] md-device too small: where's my mistake?
Heiko Wundram schrieb: You cannot manage disks = ~2TB with fdisk (i.e., DOS partition tables), as they (or rather the on-disk-structure of DOS partition tables) have an inherent limitation in the maximum number of LBA48-blocks they can address. I'd presume that because of this inherent limitation, fdisk is reporting the wrong total size (2TB+774G+epsilon ~ 3TB; sounds like somewhere someone is doing a modulo operation, possibly), and completely off values for heads/sectors. Anyway, md-devices cannot be partitioned anyway (of course you can write a partition table on them, but the kernel won't use that to create md2-1,-2, etc.), so using fdisk is wrong. If you want to check the real size of the device, don't use fdisk, but rather use blockdev --getsize64 /dev/md2 which shows you the byte-count of the corresponding volume, and which I think will be 3TB, as you want it to be. Nope, it did show the same 774 GB. If you want to subpartition large devices, use lvm(2), which does not have the 2TB limitation on size. Hope this helps! Thanks for your explanations and suggestions ... but ... I just now received a reply to my posting on the german list, the mistake was that CONFIG_LBD was not set in my kernel. Now I get: # blockdev --getsize64 /dev/md2 2973068230656 # fdisk -l Platte /dev/md2: 2973.0 GByte, 2973068230656 Byte Thanks anyway! Stefan
[gentoo-user] md-device too small: where's my mistake?
Greets, I currently try to setup a md-device containing of 4 partitions on 4 SATA-drives: # fdisk -l | grep sd Platte /dev/sda: 1000.2 GByte, 1000204886016 Byte /dev/sda1 1 2 16033+ fd Linux raid autodetect /dev/sda2 3 21 152617+ 82 Linux Swap / Solaris /dev/sda3 221116 8795587+ fd Linux raid autodetect /dev/sda41117 121601 967795762+ fd Linux raid autodetect Platte /dev/sdb: 1000.2 GByte, 1000204886016 Byte /dev/sdb1 1 2 16033+ fd Linux raid autodetect /dev/sdb2 3 21 152617+ 82 Linux Swap / Solaris /dev/sdb3 221116 8795587+ fd Linux raid autodetect /dev/sdb41117 121601 967795762+ fd Linux raid autodetect Platte /dev/sdc: 1000.2 GByte, 1000204886016 Byte /dev/sdc1 1 2 16033+ fd Linux raid autodetect /dev/sdc2 3 21 152617+ 82 Linux Swap / Solaris /dev/sdc3 221116 8795587+ fd Linux raid autodetect /dev/sdc41117 121601 967795762+ fd Linux raid autodetect Platte /dev/sdd: 1000.2 GByte, 1000204886016 Byte /dev/sdd1 1 2 16033+ fd Linux raid autodetect /dev/sdd2 3 21 152617+ 82 Linux Swap / Solaris /dev/sdd3 221116 8795587+ fd Linux raid autodetect /dev/sdd41117 121601 967795762+ fd Linux raid autodetect I want a RAID5-device md2 (without hotspare, while md1 *has* a hotspare-partition) containing the partitions sd?4. I have now: cat /proc/mdstat Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4] md1 : active raid5 sdd3[3](S) sdc3[2] sdb3[1] sda3[0] 17591040 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU] md2 : active raid5 sdd4[3] sdc4[2] sdb4[1] sda4[0] 2903386944 blocks level 5, 64k chunk, algorithm 2 [4/4] [] md0 : active raid1 sdb1[1] sda1[0] 15936 blocks [2/2] [UU] md2 is the one that gives me headaches. AFAI understand it should be about 3TB in size, but it is only 774 GB # fdisk -l /dev/md2 Platte /dev/md2: 774.0 GByte, 774044975104 Byte 2 Köpfe, 4 Sektoren/Spuren, 188975824 Zylinder Einheiten = Zylinder von 8 × 512 = 4096 Bytes Disk identifier: 0x Why? # cat /proc/version Linux version 2.6.25-gentoo-r8 ([EMAIL PROTECTED]) (gcc version 4.1.2 (Gentoo 4.1.2 p1.1)) #2 SMP Wed Oct 22 11:07:19 CEST 2008 Maybe anything wrong in my kernel? I also noticed that only 1G RAM of 2 had been detected as I had no SMP-support in the previous kernel ... now I have ... Thanks for any pointer Stefan
