ISCSI/LVM question

[tkintenn]

I've been playing with proxmox and absolutely love it.

If we goto production with it I am curious how others are setting up their storage. I started out creating seperate iSCSI disks on my nas, Prod, Test, Report and attaching those to proxmox. There were each designated for individual vm's. That worked ok and was extremely fast. Then read through the forums that some of my misgivings about this setup would be resolved by creating LVM's over top of the iscsi targets. Then reading the forums again i found i could easily resize my lvms using pvresize.

How are others utilizing this? Is there a problem with multiple iscsi connections to a pm ve server? The disadvantage I didn't like about multiple iscsi disks was the chance of high network usage causing latency from what could be 4 open connections to the nas. Oh yeah, I'm new to iSCSI so i'm still learning about that as well. NFS failed quite a bit so I didn't try to use it all as iSCSI worked great from the get go.

Just looking to get a feel for how others setup storage and what they like and dislike. Thanks.

 

[tkintenn]

So I've discovered something new, that's probably in a manual somewhere. You don't seem to be able to create multiple LVM's on one iSCSI, atleast the web interface is stopping me. interesting.

 

[m.ardito]

So I've discovered something new, that's probably in a manual somewhere. You don't seem to be able to create multiple LVM's on one iSCSI, atleast the web interface is stopping me. interesting.

afaik, LVM over ISCSI works like you setup one big ISCSI LUN, then connect that on pve as iscsi storage
then create a LVM storage over that iscsi storage.

then you create VMs of whatever disk size and set the LVM storage to hold them
pve creates a LV for each disk automatically.

This is what I use most, but don't support "point in time" snapshot. for that you need qcow2 disks and so NFS or other filsystem storages (not ISCSI).

hth
Marco

 

[tkintenn]

Ahhh ok. this makes much more sense. So is there any reason to have multiple scsi connections? Or any advantage or am i just wasting bandwidth at that point?

also, i have already disconnected, via the webgui, the secondary iscsi connection. However my NAS still shows a connection. How do i find this and remove it from the pve server? it doesn't show up as storage any longer.

 

[m.ardito]

Ahhh ok. this makes much more sense. So is there any reason to have multiple scsi connections? Or any advantage or am i just wasting bandwidth at that point?

well, you could want to use more than only one nas/san to not put all your eggs in one basket and use two separate network connections, if this works for you better

you could also make one LUN for a VM and all its disk over there put is a bit of a PITA and pve helps so much in this...

also, i have already disconnected, via the webgui, the secondary iscsi connection. However my NAS still shows a connection. How do i find this and remove it from the pve server? it doesn't show up as storage any longer.

this also I found, and is annoying, pve creates connections but does not remove them when unused...
you have to use iscsiadm to log off from the cli, or at leas I don't know any other way. Once setup, it is not every day job, though

Marco