[RndTbl] Getting disk sizes of mountpoints
Kevin McGregor
kevin.a.mcgregor at gmail.com
Wed Feb 21 19:40:43 CST 2024
No worries. I’d just use whatever, but I’m trying to come up with something
I can use via Ansible across a couple of hundred machines. I need precise
numbers for work reasons. 🙂
On Wed, Feb 21, 2024 at 18:47 Vijay Sankar <vsankar at foretell.ca> wrote:
> Thanks for the explanation Kevin and sorry for the noise. I tend to use
> disklabel to see the size of each partition or physical disk info and df
> just to see how much is on each mount point as my needs are quite trivial.
> However, I am an OpenBSD user and don’t know as much about Linux etc.
>
> Sent from my iPhone
>
> On Feb 21, 2024, at 18:23, Kevin McGregor <kevin.a.mcgregor at gmail.com>
> wrote:
>
>
>
> Fair question. On the same system, df -h gives:
> Filesystem Size Used Avail Use% Mounted on
> udev 465M 0 465M 0% /dev
> tmpfs 99M 7.8M 91M 8% /run
> /dev/mapper/vg0-root 15G 3.3G 12G 22% /
> tmpfs 493M 0 493M 0% /dev/shm
> tmpfs 5.0M 0 5.0M 0% /run/lock
> tmpfs 493M 0 493M 0% /sys/fs/cgroup
> /dev/mapper/vg1-data 98G 61M 93G 1% /mnt/data
> /dev/mapper/vg0-var 5.0G 956M 4.1G 19% /var
> tmpfs 99M 0 99M 0% /run/user/1000
>
> Where '/' and 'var' are correct, but /mnt/data shows as 98G instead of
> 100G. I'm looking for the disk sizes, not the file system sizes.
>
> This is actually a VM, and I can get the exact disk sizes from VMware...
> but not the mount points. And since / and /var are on the same disk, the
> VMware info lacks the detail I need.
>
> Major device 253 seems to be used for LVM devices, so assuming that misses
> things like "sda2 8:2 0 2G 0 part /boot", which I'd
> also like to account for. Another system, for example, has
> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINTS
> sda 8:0 0 50G 0 disk
> ├─sda1 8:1 0 1M 0 part
> ├─sda2 8:2 0 2G 0 part /boot
> └─sda3 8:3 0 48G 0 part
> ├─ubuntu--vg-root 253:0 0 24G 0 lvm /
> └─ubuntu--vg-var 253:1 0 24G 0 lvm /var
> sr0 11:0 1 1024M 0 rom
>
> And from that I would want
> /boot 2G
> / 24G
> /var 24G
> which adds up to 50G (sda)
>
> lsblk -e 7 | grep '/' | awk '{ print $NF, $4 }'
> basically works (for my sample of two systems), but I don't know how
> reliable assuming grep '/' is going to be for what I want.
>
>
> On Wed, Feb 21, 2024 at 4:44 PM Vijay Sankar <vsankar at foretell.ca> wrote:
>
>> Doesn’t df -h give that info? Sorry if I misunderstood your question.
>>
>> Sent from my iPhone
>>
>> On Feb 21, 2024, at 16:36, Kevin McGregor <kevin.a.mcgregor at gmail.com>
>> wrote:
>>
>>
>> With 'lsblk' I can get something like this:
>> NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
>> sda 8:0 0 20G 0 disk
>> └─sda1 8:1 0 20G 0 part
>> ├─vg0-root 253:0 0 15G 0 lvm /
>> └─vg0-var 253:1 0 5G 0 lvm /var
>> sdb 8:16 0 100G 0 disk
>> └─sdb1 8:17 0 100G 0 part
>> └─vg1-data 253:2 0 100G 0 lvm /mnt/data
>> sr0 11:0 1 1024M 0 rom
>>
>> What I'm looking for is output like:
>> / 15G
>> /var 5G
>> /mnt/data 100G
>>
>> So I just want the size of the block devices which are actually mounted.
>> I'm wondering what is the most reliable way to produce the second output. I
>> can just grep for 'lvm', but I can't guarantee the mounts are all LVM type.
>> I can grep for ' 253:', but is the 253 going to be reliable? What does 253
>> even mean?
>>
>> From https://www.kernel.org/doc/html/latest/admin-guide/devices.html :
>>
>> 240-254 block LOCAL/EXPERIMENTAL USE
>> Allocated for local/experimental use. For devices not
>> assigned official numbers, these ranges should be
>> used in order to avoid conflicting with future assignments.
>>
>> ... which isn't encouraging. Is that list outdated? grep for '/'s?
>>
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