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Accepted
mr.zog
Asked: 2019-04-25 08:48:00 +0800 CST

Is it possible to check the available space of a Linux logical volume without mounting it?

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I have a project that requires me to shrink the root and home volumes on an existing CentOS 6 install to make room for a CentOS 7 install on a customer's bare metal host. Yes, I know what a bad idea this is. We ought to be shipping our customer a brand new, fully configured server.

Anyhow, I'm wondering if there's any magic utility that can scan unmounted disk volumes and report back how much free space or (or what percentage) can be used when I eventually run lvreduce. Anaconda must do this but how to I use anaconda in the %pre section of my kickstart config file?

Thanks.

centos7

1 Answers

  1. Best Answer

    If the filesystem was ext[234] I would guess you could probably do something like tune2fs -l /dev/devicename.

    # tune2fs -l /dev/sda3 | grep -i 'block'
Block count:              9865984
Reserved block count:     493299
Free blocks:              8871467
First block:              0
Block size:               4096
Reserved GDT blocks:      1024
Blocks per group:         32768
Inode blocks per group:   511
Flex block group size:    16
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
Journal backup:           inode blocks
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