[pve-devel] adding libiscsi to qemu-kvm ?

[Alexandre DERUMIER]

>>For me this is a step back.
I disagree.This is a huge step for direct iscsi luns.
I can tell you that it's currently a pain to manage with a lot of luns.


>>We lose snapshot capabilities and multipath support? 

which snapshot capabilities ? I'm talking about iscsi devices, not lvm on top of iscsi.
Snapshots/cloning must be done on the san side. (nexenta,netapp,.. have api to do this).


About multipath, I can tell you that with 500luns, it's pretty impossible to manage. (it's using a lot of cpu and hanging sometimes)
In fact,i'm going to implemenent lacp soon, I have add too much problem with multipath daemon.


Currently if something goes wrong (failover of san controller or network saturation), with a lot of luns, kernel take a lot of time to restore device access.
last time, I have a 30sec failover, kernel+multipath have take 5min to restore device access...
With libscsi, it take around 5sec to restore access.




>> And as soon an ceph/sheepdog is stable you will dump iscsi anyways? 

Sure, but I don't want to put to trash a 100.000$ san, right ? ;)
Migrate to ceph/sheepdog will take time. 
For ceph, i got around 14000iops, not enough for me and sheepdog seem to be not enough stable.

----- Mail original ----- 

De: "Dietmar Maurer" <dietmar at proxmox.com> 
À: "Alexandre DERUMIER" <aderumier at odiso.com>, pve-devel at pve.proxmox.com 
Envoyé: Mardi 10 Juillet 2012 06:33:33 
Objet: RE: [pve-devel] adding libiscsi to qemu-kvm ? 

> The only thing different is that they are no multipath support. (It need to be 
> manage inside the guest, or using lacp/bonded san network). 
> 
> 
> What do you think about it ? 

For me this is a step back. We lose snapshot capabilities and multipath support? 

And as soon an ceph/sheepdog is stable you will dump iscsi anyways? 

- Deitmar 




-- 

-- 



	

Alexandre D e rumier 

Ingénieur Systèmes et Réseaux 


Fixe : 03 20 68 88 85 

Fax : 03 20 68 90 88 


45 Bvd du Général Leclerc 59100 Roubaix 
12 rue Marivaux 75002 Paris