[linux-lvm] mixed ssd/disk szenario question: moving lv from ssd ->disk?

[linux-lvm] mixed ssd/disk szenario question: moving lv from ssd ->disk?

[Oliver Rath]

Hi list,

I have an vg over multiple disks (ssd and standard disks) and a big
thinpool-volume inside. From thin thinpool i create a lot of snaps
(>200), which are normally explizit placed on the ssd (i can select the
pv-path on lvcreate).

Now, after a time some of these snaps i dont need on the fast device and
want to mv them to a slow pv (standard disk) as a kind of backup.

Ist it possible to "move" a lv from the ssd to a disk, if both devices
are part of my vg?

Tfh!
Oliver

Re: [linux-lvm] mixed ssd/disk szenario question: moving lv from ssd ->disk?

[matthew patton]

I think 'lvconvert --replace /dev/<ssd> VG/LV /dev/<slow disk>'
will do what you want.

Re: [linux-lvm] mixed ssd/disk szenario question: moving lv from ssd ->disk?

[Oliver Rath]

Hi Matthew,

thank you for the hint! In the lvconvert-manpage they write:

"This option is only available  to  RAID  segment types (e.g.  raid1,
raid5, etc)"

So I assume this will not work with thinpool-devices, but using raid
with this trick is another good idea.

Tfh!
Oliver


Am 18.11.2014 um 17:55 schrieb matthew patton:
> I think 'lvconvert --replace /dev/<ssd> VG/LV /dev/<slow disk>'
> will do what you want.
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] mixed ssd/disk szenario question: moving lv from ssd ->disk?

[Oliver Rath]

Hi Matthew,

i have to correct my last email: This works also with thinpool-lvs!
Better said: There was no error message executing  this command. Will
walk on this way for more reults. Maybe the lvconvert-manpage is outdated?

Tfh!
Oliver


Am 18.11.2014 um 17:55 schrieb matthew patton:
> I think 'lvconvert --replace /dev/<ssd> VG/LV /dev/<slow disk>'
> will do what you want.
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://www.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Re: [linux-lvm] mixed ssd/disk szenario question: moving lv from ssd ->disk?

[Zdenek Kabelac]

Dne 23.11.2014 v 12:47 Oliver Rath napsal(a):
> Hi Matthew,
>
> i have to correct my last email: This works also with thinpool-lvs!
> Better said: There was no error message executing  this command. Will
> walk on this way for more reults. Maybe the lvconvert-manpage is outdated?
>
> Tfh!
> Oliver

Hi


I'm somehow missing the point here.

Could you please show us  'lvs -a -o+seg_pe_ranges'

Normally when you make a thin volume snapshot, the snapshot is sharing your 
blocks within thin-pool.  So no space is allocated on any SSD for this.
(And you cannot specify which block will be used in a thin-pool)

If you would be using 'old-snapshot' which does allocate 'extra' space for COW 
block -then you would probably see horrible performance with 200 snapshots...

And finally - standard command for moving extents around in a VG is - 'pvmove'.


Regards

Zdenek