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Re: [Xen-users] Xen + IPv6 + Netapp = NFS read problem



On Mon, Nov 19, 2012 at 12:08 AM,  <G.Bakalarski@xxxxxxxxxx> wrote:
> The problem is the following:
>
> THE READ PERFORMANCE OF BACKUP SERVER IS DRAMATICALLy LOW: TYPICAL SEQUENTIAL
> READ FROM NETAPP SHARE FALLS DOWN TO 5-10MBytes/s !!!!!!!!!!!!!!!!!!!!!!!
> On the other hand WRITE PERFORMANCE IS OK i.e 80-100MBytes/s

Writing in all capitals won't get you faster response, you know. It'd
only get you marked as rude or annoying
http://en.wikipedia.org/wiki/All_caps#Computing

> We made the following tests:
>
> 1) Netapp_IPv6 - bare_metal_server_IPv6 - ALL FINE (full network speed)

Is this the same server? If no, please retest using the same server
(or at least the same NIC)

> 6) Linux_server_IPv6 (regadless bare metal, dom0 or domU) -
>                - Xen_domU-IPv6(via_bridge) - ALL FINE

So mounting a normal linux nfs share is fine, but mounting netapps share sucks?

> Any hints?

Since mounting a linux nfs share works fine, you should check with
netapp just in case they have some experience or bug entry on that.

Other than that, some network-related problems usually go away if you
turn off checksum in ALL interfaces involved (dom0's nic, the bridge,
and the virtual interfaces)

> We think of throwing Xen away :-/


Perhaps you should.

In the end, use whatever works. It works fine for other people,
although perhaps it's because they don't use the same combination as
yours. Had you use vendor-supported xen solution, this might be a good
time to file a bug report. Since you don't, your generic choice is to
pick one of:
- be patient. Just in case someone has similar problem and solved it
already. Shouting or writing all caps won't help you here.
- try latest versions of xen and kernel from git. Just in case the
problem is solved in latest upstream.
- try some generic workarounds (e.g. disable checksum)
- throw away one of the things that caused the problem (in your case,
it's either xen or netapp) and stick with working solutions.

-- 
Fajar

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