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Re: [linux-lvm] N00b Question: Logical Volume without a Logical Volume Group ?



Marek Podmaka wrote:
Hello,

Wednesday, November 2, 2011, 11:18:50, James Hawtin wrote:

Personally even with LVM I would still write a partition table the disk,
this helps show the disk as being used to other system administrators,
however there would be one partition on it of type 8e, and on that I would create a PV (physical volume), this PV can then be used to create

How do you extend the PV then? For example extend the LUN on storage
or just resize a RAID1+0 set by adding 2 new disks... Resizing the
block device is no problem, resizing the PV also, but to resize the
PV, you need to resize the partition also - and if I remember well,
the kernel won't re-read the new partition table while it is used...


I never have need to extend a PV, I just add a new piece of disk (LUN) to the server, create a PV on that and extend the volume group and LV. There is pvresize if you really want to extend an lun, that could be used after making the disk larger or fdisking more space, however I never have need to do that, I pretty much always present a new lun. You can also create a second partition on a larged disk and then create a PV on that too... LVM is designed to join all your bits of disk together, so you don't have to need one continue peice of space to provide the disk.

Using pvmove I can allocate a larger new piece of disk and online move all the data from an old pv to a new one as well. In my experence with working with large san system rays are not in general extended, whole new ones are added instead. Personally I would not extend and existing array with an additional mirror concat, I would prefer to use raid 10 or use software striping in LVM with seperately presented LUNs for each mirrored pair as that would work the disk harder.

James


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