[linux-lvm] calculating free capacity from pvdisplay and lvdisplay
Ray Morris
support at bettercgi.com
Wed Aug 11 06:10:31 UTC 2010
> B. Thus the total full space would come to 4.89 TB. But the sum of
> full
> space of all my LV's is only around 3 TB (based on the output of df)
It's the same thing as making a new partition covering your whole drive,
then wondering why fdisk says you can't make another partition. Just
because you haven't stored files in that partition, it's still takes
up the whole drive.
df shows that your LVs take up 8.6TB: 6TB + 600 GB + 2 TB.
Therefore, you are using 8.6TB of disk space for those LVs.
Some of the space WITHIN each LV might not be used for files,
but it has been dedicated to that LV.
df also shows that the filesystems on the LVs have free space for
more files. So you can put more files on those LVs, which is a
different thing than having space to make more LVs.
I'm not good at explaining things, so sometimes I try explaining three
different ways. I have six cereal boxes, each half empty. I put the
boxes in a bag. The bag is now full. The cereal boxes may not be full,
but they fill up the bag. The cereal boxes are your half empty LVs and
the bag is your drives.
Layers:
hard drive
partition (can be skipped)
physical volume
volume group
logical volume
file system
--
Ray Morris
support at bettercgi.com
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On 08/10/2010 09:25:15 PM, Rahul Nabar wrote:
> Some of the physical volumes show "Allocatable yes (but
> full)" while others don't. How does one relate this to the actual
> capacity? THe reason I am confused is that 3 of my PV's show up as
> full and each is 1.63 TB. Thus the total full space would come to 4.89
> TB. But the sum of full space of all my LV's is only around 3 TB
> (based on the output of df)
>
> I've reproduced the outputs of pvdisplay, lvdisplay and df below.
>
> I'm confused! Any pointers?
>
> --
> Rahul
>
>
> [root at eustorage ~]# pvdisplay
> --- Physical volume ---
> PV Name /dev/sdb
> VG Name euclid_highperf_storage
> PV Size 1.63 TB / not usable 4.00 MB
> Allocatable yes (but full)
> PE Size (KByte) 4096
> Total PE 428351
> Free PE 0
> Allocated PE 428351
> PV UUID wDdbmP-2n5m-98HD-Ewqk-Q3y0-lnMf-rsaVXt
>
> --- Physical volume ---
> PV Name /dev/sdc
> VG Name euclid_highperf_storage
> PV Size 1.63 TB / not usable 4.00 MB
> Allocatable yes (but full)
> PE Size (KByte) 4096
> Total PE 428351
> Free PE 0
> Allocated PE 428351
> PV UUID 75i75q-2rec-2FMf-eyPa-W0nF-zFHH-PIAvvc
>
> --- Physical volume ---
> PV Name /dev/sdd
> VG Name euclid_highperf_storage
> PV Size 1.63 TB / not usable 4.00 MB
> Allocatable yes (but full)
> PE Size (KByte) 4096
> Total PE 428351
> Free PE 0
> Allocated PE 428351
> PV UUID vo2Jh2-PfFC-eOj4-GYnP-Jx1I-Sisu-2nY4lC
>
> --- Physical volume ---
> PV Name /dev/sde
> VG Name euclid_highperf_storage
> PV Size 1.63 TB / not usable 4.00 MB
> Allocatable yes
> PE Size (KByte) 4096
> Total PE 428351
> Free PE 38140
> Allocated PE 390211
> PV UUID EK7cvF-IZjf-PJVw-d2RR-lCdt-kOSD-iqFtOf
>
> --- Physical volume ---
> PV Name /dev/sdf
> VG Name euclid_highperf_storage
> PV Size 1.63 TB / not usable 4.00 MB
> Allocatable yes
> PE Size (KByte) 4096
> Total PE 428351
> Free PE 140607
> Allocated PE 287744
> PV UUID fQXN8S-HhYu-weoq-kbuz-BrxZ-6WQk-6ydBDw
>
> --- Physical volume ---
> PV Name /dev/sdg
> VG Name euclid_highperf_storage
> PV Size 1.63 TB / not usable 4.00 MB
> Allocatable yes
> PE Size (KByte) 4096
> Total PE 428351
> Free PE 140607
> Allocated PE 287744
> PV UUID i7GD1d-rbd2-efKd-uK3u-D3S2-BxJv-UkrNve
>
> [root at eustorage ~]# df -h
> Filesystem Size Used Avail Use% Mounted on
> /dev/sda2 76G 8.6G 64G 12% /
> /dev/sda6 19G 365M 17G 3% /var
> /dev/sda5 15G 165M 14G 2% /tmp
> /dev/sda1 487M 17M 445M 4% /boot
> tmpfs 24G 0 24G 0% /dev/shm
> /dev/mapper/euclid_highperf_storage-LV_home
> 6.0T 1.4T 4.4T 24% /home
> /dev/mapper/euclid_highperf_storage-LV_export
> 591G 17G 550G 3% /opt
> /dev/mapper/euclid_highperf_storage-LV_polhome
> 2.0T 1.5T 386G 80% /polhome
> [root at eustorage ~]# lvdisplay
> --- Logical volume ---
> LV Name /dev/euclid_highperf_storage/LV_home
> VG Name euclid_highperf_storage
> LV UUID gu7yo1-TYYr-ucHG-QSDk-y8HD-ETrs-Z5kCk9
> LV Write Access read/write
> LV Status available
> # open 1
> LV Size 6.00 TB
> Current LE 1572864
> Segments 1
> Allocation inherit
> Read ahead sectors auto
> - currently set to 1536
> Block device 253:0
>
> --- Logical volume ---
> LV Name /dev/euclid_highperf_storage/LV_export
> VG Name euclid_highperf_storage
> LV UUID 1lktLy-Hgn3-qS1m-41VJ-5kNY-DMyb-1ri4Th
> LV Write Access read/write
> LV Status available
> # open 1
> LV Size 600.00 GB
> Current LE 153600
> Segments 1
> Allocation inherit
> Read ahead sectors auto
> - currently set to 1536
> Block device 253:1
>
> --- Logical volume ---
> LV Name /dev/euclid_highperf_storage/LV_polhome
> VG Name euclid_highperf_storage
> LV UUID xqpOX5-HFey-H0qi-NgjP-NVS7-FwDb-zbiK8m
> LV Write Access read/write
> LV Status available
> # open 1
> LV Size 2.00 TB
> Current LE 524288
> Segments 4
> Allocation inherit
> Read ahead sectors auto
> - currently set to 256
> Block device 253:2
>
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