How to add additional disks to an existing local storage repository?

[steve leung]

Hi all,

 

I successfully followed the instructions from 

 

    https://support.citrix.com/article/CTX121313?recommended

 

to create a new local storage repository with XE commands.

 

Now I want to add additional disks to this newly created storage repository.

 

I could not find anything in the Internet on this subject.

 

Any pointer is appreciated?

 

I guess I can try to extend the related logical volume but it seems to be touching too much internals; not sure if it is the correct approach.

 

Thanks.

 

Steve

 

 

 

 

[Tobias Kreidl]

Hi, Steve and welcome first off to the forum!

 

By adding disks, you mean expanding the volume, correct? Unless you have some sort of local hardware RAID, I'd recommend against this and rather create separate SRs on separate volumes/disks. It is of course possible to extend an LVM volume, but it's a more involved process and again, without redundancy that you don't get by for example just concatenating disks, you put the system at some risk in the event there is storage corruption.

 

-=Tobias

[steve leung]

Yes I mean expand the existing local storage repository.

 

I understand the reliability factors but if I really want to do it, how to proceed?

 

Are there XE commands to do it?

 

Or do I use standard LVM commands to make it happen?

 

On a slightly different topic, if I create a separate SR, how would it make the system more reliable if the disks are going to crash anyway?

 

Thanks.

 

Steve

[Alan Lantz]

You could use separate disks to make another raid or a mirror and then add a new local SR. That would be the easiest approach. If i were to expand existing local storage I would prefer to move that VM data to remote storage or back it up and reinstall XenServer fresh once the array is expanded. I'm sure you could do that easier via LVM if you are command line savvy, but I'm not so I would reinstall XenServer.

 

--Alan--

[steve leung]

The reason I asked this question:

 

During installation of xenserver, the installer creates an initial local SR for you, and if you provide multiple local disks, it will add them all to the same SR.

 

Since the SR can support multiple disks already, how to add more if there is a need down the road.

 

Intuitively it seems to me a common use case for xenserver users but I guess it is not (I am new to Xen world).

 

Thanks.

 

Steve

[Alan Lantz]

Yes, you're right, its an area of XenServer that could use some improvement. The addition/modification of local storage once defined at installation time is thereafter inflexible where it really shouldn't be with LVM being leveraged.

 

--Alan--

[Tobias Kreidl]

Yes, the only opportunity you have to consolidate multiple local disks into an SR is at installation time.  Otherwise, you need to use LVM and are on your own with LVM guides, which can be found on multiple CentOS blogs.

 

-=Tobias

[Marc ONeill]

Yes, the only opportunity you have to consolidate multiple local disks into an SR is at installation time.  Otherwise, you need to use LVM (assuming you're not using the ext option) and are on your own with LVM guides, which can be found on multiple CentOS blogs.

 

-=Tobias

 

 

The EXT local SR sits on LVM anyway so regardless you could expand the local SR to include more disks by extending the PV/VG to include the new disk and expanding the LV. Then you just resize the FS to the full extent of the LV.

 

You could use the standard LVM commands to achieve this but I wouldn't do it with information on the SR or without a backup so a fresh install would be best.

[Dirk H.]

I'm trying to use the standard LVM commands to expand the local SR.  The first command I use is "pvcreate /dev/sdb" and I receive the error:
"pvcreate /dev/sdb: Command not permitted while global/metadata_read_only is set."  Please help.