Hi, I am setting up a small installation of opennebula with
sharedstorage using iSCSI. THe storage is Equilogic EMC with two
controllers. Nowadays we have only two host servers so we use backed
direct connection between storage and each server, see attachment. For
this purpose we set up dm-mult
Hi,
lvm metadata[1] is simply stored on the disk. In the setup we are
discussing this happens to be a shared virtual disk on the storage,
so any other hosts that are attaching the same virtual disk should see
the changes as they happen, provided that they re-read the disk. This
re-reading step is
Thank you. does it mean, that I can distribute metadata files located in
/etc/lvm on frontend onto other hosts and these hosts will see my
logical volumes? Is there any code in nebula which would provide it? Or
I need to update DS scripts to update/distribute LVM metadata among
servers?
Thank
Oh snap, that sounds great I didn't know about that.. it makes all
easier. In this scenario only frontend can work with LVM, so no issues
of concurrent change. Only one last think to make it really safe against
that. Is there any way to suppress LVM changes from hosts, make it read
only? And le
Hi,
thank you both for such a high quality and educational thread. I wasn't
aware of the possibility of configuring the LVM metadata in a host as
read-only, but it fits beautifully with OpenNebula.
Mihály, would you like to share your experiences somewhere in the
OpenNebula community? wiki.openne
Hi!
You need to look at locking_type in the lvm.conf manual [1]. The
default - locking in a local directory - is ok for the frontend, and
type 4 is read-only. However, you should not forget that this only
prevents damaging thing by the lvm commands. If you start to write
zeros to your disk with th
Hi, I have just set it up having two hosts with shared blockdevice. On
top of that LVM, as discussed earlier. Triggering lvs I can see all
logical volumes. When I create a new LV on the other server, I can see
the LV being inactive, so I have to run lvchange -ay VG/LV enable it
then this LV ca
Hi!
We solve this problem via hooks that are activating the LV-s for us
when we start/migrate a VM. Unfortunately I will be out of office
until early next week but then I will consult with my colleague who
did the actual coding of this part and we will share the code.
Cheers
Mihály
On 24 January
Hi,
Well, if you can run the lvs or lvscan on at least one server
successfully, then the metadata is probably fine.
We had similar issues before we learned how to exclude unnecessary
block devices in the lvm config.
The thing is that lvscan and lvs will try to check _every_ potential
block device
Hi,
We have a custom datastore, and transfer manager driver, which runs the
lvchange command when it is needed.
In order to work, you have to enable it in oned.conf.
for example:
DATASTORE_MAD = [
executable = "one_datastore",
arguments = "-t 10 -d fs,vmware,iscsi,lvm,shared_lvm"]
TM_M
Hi, thank you. I checked source codes and I found it is very similar to
LVM TM/Datastore drivers which is facilitated in ONE already only you
added lvchange -ay DEV. Do you run CLVM along that or not?
I worry about parallel changes of LVM metadata which might destroy them.
From sequential beha
Hi,
We are running it without CLVM.
If you examine the ONE/lvm driver (the tm/clone script for example), you
can see, that the lvcreate command runs on the destination host. In the
shared LVM driver, all the LVM commands are running on the frontend, hence
there is no possibility of parralel change
> The other thing with the ONE/lvm driver is that it makes a snapshot in the
> clone script, while our driver makes a new clone LV. I tried to use the
> original LVM driver, and every time, I deployed a new VM, I got this error
> message:
>
> lv-one-50 must be active exclusively to create snapshot
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