[linux-lvm] half my space lost

[Ronan-Yann Lorin]

Thank you for this explanation which sounds very clear.

One more question please. I do not understand why I can not extend my VG with the
second RAID partition:
[root at fw root]# pvdisplay /dev/md/8
pvdisplay -- "/dev/md/8" is a new physical volume of 125.38 MB

[root at fw root]# vgextend secured /dev/md/8
vgextend -- INFO: maximum logical volume size is 2 Terabyte
vgextend -- ERROR: physical volume "/dev/md/8" too small for physical extent siz
e of volume group "secured"

Thanks in advance.

Koch, Steffen (steffen.koch at sphinx-electronics.de) wrote*:
>
>Hello,
>
>> [root at fw root]# vgcreate secured /dev/md/7
>> vgcreate -- INFO: using default physical extent size 32 MB
>> vgcreate -- INFO: maximum logical volume size is 2 Terabyte
>> vgcreate -- doing automatic backup of volume group "secured"
>> vgcreate -- volume group "secured" successfully created and activated
>As it is stated here an extent is 32 MB, and one extent is always lost at
>the beginning of the md (partition, disk, etc.) for metadata information.
>This should leave you with 125 MB - 32 MB = 93 MB.
>LVM volumes have to be a multiple of the extent size. So 32MB, 64 MB, 96 MB.
>As you can see your remaining space is 3 MB too little for a 3 extent
>volume, leaving you with a 2 extent volume with 2 * 32 MB = 64 MB
>
>> The size of the partition get shrink by half:
>>
>> [root at fw root]# pvscan
>> pvscan -- reading all physical volumes (this may take a while...)
>> pvscan -- ACTIVE   PV "/dev/md/7"
>>   of VG "secured"
>> [64 MB / 64 MB free]
>> pvscan -- inactive PV "/dev/md/8"
>>   is in no VG
>> [125.38 MB]
>> pvscan -- ACTIVE   PV
>> "/dev/ide/host0/bus1/target0/lun0/part13" of VG "lvm1"
>> [17 GB / 16.97 GB fr
>> pvscan -- total: 3 [17.28 GB] / in use: 2 [17.16 GB] / in no
>> VG: 1 [125.38 MB]
>>
>> Is this a known/solved problem?
>> Did I made a mistake?
>>
>> Thanks in advance for your help.
>> Regards.
>
>Hope the explanation helped.
>
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>
>

--
R.Y. Lorin
mailto:ryl at free.fr
http://les-lorin.webhop.net/