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RE: [Xen-users] RAID10 Array


  • To: <xen-users@xxxxxxxxxxxxxxxxxxx>
  • From: "Jonathan Tripathy" <jonnyt@xxxxxxxxxxx>
  • Date: Thu, 17 Jun 2010 16:18:20 +0100
  • Delivery-date: Thu, 17 Jun 2010 08:20:27 -0700
  • List-id: Xen user discussion <xen-users.lists.xensource.com>
  • Thread-index: AcsOHXsjWAA6YdqQTROvz0Ps/pqoiwAAIlpVAAAJaUAAAGJ8pAAAAh+QAAIpquoAAWPxkAAAYfeJAAA1xRU=
  • Thread-topic: [Xen-users] RAID10 Array

Sorry, I meant 3 X RAID10 (4 disks per Array) + 4 Hot Spares


From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx on behalf of Jonathan Tripathy
Sent: Thu 17/06/2010 16:12
To: Robert Dunkley; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-users] RAID10 Array

 
Hi Rob,
 
You do know best :)
 
4 X RAID10 Arrays + 4 Hot Spares it is then
 
Thanks
 
Jonathan


From: Robert Dunkley [mailto:Robert@xxxxxxxxx]
Sent: Thu 17/06/2010 16:10
To: Jonathan Tripathy
Subject: RE: [Xen-users] RAID10 Array

Hi Jonathan,

 

 

It really will come down to either testing the different configs or just picking a best guess config. I would go with 4 Raid 0s since I think your load will be spread between so many VMs that in my opinion I would rather have a bit more isolation and few more baskets with less eggs in them.

 

 

Rob

 

From: Jonathan Tripathy [mailto:jonnyt@xxxxxxxxxxx]
Sent: 17 June 2010 15:22
To: Robert Dunkley; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-users] RAID10 Array

 

Rob,

 

Regarding the number of RAID10 array to use, do you think that 2 X RAID10 arrays (6 disks each) + 4 hot spares would be a good compramise? I'm trying to get the best IOPS for the level of hardware I'm using.

 

Thanks


From: Robert Dunkley [mailto:Robert@xxxxxxxxx]
Sent: Thu 17/06/2010 14:33
To: Jonathan Tripathy
Cc: kriegisch@xxxxxxxx
Subject: RE: [Xen-users] RAID10 Array

Hi Jonathan,

 

 

Theoretical would be 2Gbit to the Nodes and 4Gbit to the Storage so 2 nodes could for example get 2gbit bandwidth each simultaneously but this does come with some loss in practice and additional CPU overhead.

 

The ATA load balance type situation described in the previous email allows 1gb to any one node from a single device on the storage server but up to 4 nodes could drag 1gbit each simultaneously from the storage server. Considering how many nodes you are planning the load balanced scenario might even be preferable to LACP/802.3AD as long as the ATAoE target software can do a good job due to potentially lower CPU overhead and easier implementation of multiple switches for redundancy.

 

None of these software decision will affect your hardware choice so its portably about time you got your hands dirty J

 

 

Rob

 

From: Jonathan Tripathy [mailto:jonnyt@xxxxxxxxxxx]
Sent: 17 June 2010 14:19
To: Robert Dunkley; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-users] RAID10 Array

 

Hi Rob,

 

And if I was to use let's say 4 teamed ports coming out of the storage server, and 2 teamed ports going into the xen node, would the max I'd get be still 1Gbit?

Thanks

 


From: Robert Dunkley [mailto:Robert@xxxxxxxxx]
Sent: Thu 17/06/2010 14:15
To: Jonathan Tripathy
Subject: RE: [Xen-users] RAID10 Array

Hi Jonathan,

 

LACP and 802.3AD are used together on those HP Soho switches. I might be wrong but LACP I think allows automatic negotiation to some degree at the switch side.

 

I have used LACP with Broadcom based NICs in Windows and the HP switch you are looking at. You only need to enable LACP on the switch ports plugged into your disk box and then the software on the server should be able to sort the rest (I enabled it with Broadcom NICs under Windows and it worked as advertised).

 

 

Rob

 

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Jonathan Tripathy
Sent: 17 June 2010 14:07
To: Adi Kriegisch; xen-users@xxxxxxxxxxxxxxxxxxx
Subject: RE: [Xen-users] RAID10 Array

 


 

 


From: Adi Kriegisch [mailto:kriegisch@xxxxxxxx]
Sent: Thu 17/06/2010 14:03
To: Jonathan Tripathy
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] RAID10 Array

Hi!

> Looking at this page https://help.ubuntu.com/community/HighlyAvailableAoETarget
> they seem to have made a linux "bond" called bond0 and are telling the AoE
> target to use that. This confuses me...
> Would it be of any benifit to create a "mode 4" bond and use 802.3ad with ATA
> over Ethernet? Or would that be just a waste, when AoE can use the interfaces
> directly?
ggaoed for example can handle multiple interfaces in the configuration and
is designed to deliver highest performance with for example automatically
load balancing over several NICs.
If you want to use vblade you might be better off using bonding because
vblade cannot handle several interfaces in one instance. You'll get another
performance penalty when using several instances of vblade listening on
different interfaces.
I am not sure if LACP enhances performance in your case: I think from one
server to the other you will only get 1GBit; for LACP to work as expected
you need many-to-many or many-to-one connections. All pakets belonging to a
connection will use the same wire. This article has some
details: http://serverfault.com/questions/8512/multiplexed-1-gbps-ethernet
also Wikipedia has some information on this.

Another thing is that you loose the ability of having a redundancy in the
switching backend.

-- Adi

-------------------------------------------------------------------------------------------------------------------

So if I use ggaoed and just put all 4 NICs into its config file, that should allow me to get 4Gbit of bandwidth? And no configuration is required on the switch?

BTW, does 802.3ad "mode 4" use LACP? Or I am getting mixed up?

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SAQ is the trading name of SEMTEC Limited. Registered in England & Wales
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Registered Office: 18 Chapel Street, Petersfield, Hampshire GU32 3DZ
SAQ is the trading name of SEMTEC Limited. Registered in England & Wales
Company Number: 06481952

 

http://www.saqnet.co.uk AS29219

SAQ Group Delivers high quality, honestly priced communication and I.T. services to UK Business.

Broadband : Domains : Email : Hosting : CoLo : Servers : Racks : Transit : Backups : Managed Networks : Remote Support.

 

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