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Am Wednesday 22 October 2008 15:58:44 schrieb Stefan G. Weichinger: |
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> md2 is the one that gives me headaches. AFAI understand it should be |
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> about 3TB in size, but it is only 774 GB .... |
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> |
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> # fdisk -l /dev/md2 |
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> |
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> Platte /dev/md2: 774.0 GByte, 774044975104 Byte |
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> 2 Köpfe, 4 Sektoren/Spuren, 188975824 Zylinder |
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> Einheiten = Zylinder von 8 × 512 = 4096 Bytes |
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> Disk identifier: 0x00000000 |
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> |
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> |
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> Why? |
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You cannot manage disks >= ~2TB with fdisk (i.e., DOS partition tables), as |
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they (or rather the on-disk-structure of DOS partition tables) have an |
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inherent limitation in the maximum number of LBA48-blocks they can address. |
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I'd presume that because of this inherent limitation, fdisk is reporting the |
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wrong total size (2TB+774G+epsilon ~ 3TB; sounds like somewhere someone is |
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doing a modulo operation, possibly), and completely "off" values for |
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heads/sectors. |
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|
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Anyway, md-devices cannot be partitioned anyway (of course you can write a |
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partition table on them, but the kernel won't use that to create md2-1,-2, |
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etc.), so using fdisk is wrong. |
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|
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If you want to check the "real" size of the device, don't use fdisk, but |
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rather use |
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blockdev --getsize64 /dev/md2 |
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which shows you the byte-count of the corresponding volume, and which I think |
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will be 3TB, as you want it to be. |
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If you want to subpartition large devices, use lvm(2), which does not have the |
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2TB limitation on size. |
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Hope this helps! |
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-- |
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Heiko Wundram |
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hackerkey://v4sw7CHJLSUY$hw5ln5pr7FOP$ck2ma9u7FL$w3DVWXm0l7GL$i65e6t3EMRSXb7ADORen5a26s5MSr2p-6.62/-6.56g5AORZ |
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