[linux-lvm] calculating free capacity from pvdisplay and lvdisplay
Daksh Chauhan
um.daksh at gmail.com
Wed Aug 11 22:26:18 UTC 2010
This is interesting, and I understand your explaination Ray... But,
how can I figure out how much data is on each PVs??
I have something similar setup, and I have scripts (and cacti) to see
disk IO for each PVs, but I would really like to see how much data is
on each PV...
Thank you,
> Date: Wed, 11 Aug 2010 01:10:31 -0500
> From: Ray Morris <support at bettercgi.com>
> To: LVM general discussion and development <linux-lvm at redhat.com>
> Subject: Re: [linux-lvm] calculating free capacity from pvdisplay and
> lvdisplay
> Message-ID: <1281507031.21952.1 at raydesk1.bettercgi.com>
> Content-Type: text/plain; charset=us-ascii; DelSp=Yes; Format=Flowed
>
>> 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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>> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>>
>>
>
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