How do you connect an MD3000i to a PowerEdge server?

Thanks Mohan :) And this is the standard way of doing it? Im sure I read on the vmware forum that using a HBA gave much better performance (although unless using ethernet is going to noticably make things slow then I dont really care too much about performance)   Thanks

Well, depends on what you call standard right;).

Yes, the MD3000 will have better performance. SAS is a 3Gig interface and highly controlled in terms of length of cable etc.

However, iSCSI is more flexible. iSCSI also does not require any special additional hardware or cables. So, it works out cheaper too. Performance with iSCSI is not too bad either (especially with Gigabit ethernet). However, with a single cable from each host, you will be limiting it to an extent.

-Mohan

 

Just to further clarify,

The Dell MD3000 uses the SAS protocol to connect to a server. They are directly connected to a server using SAS cables through a SAS 5/E HBA..

The Dell MD3000i uses iSCSI (http://en.wikipedia.org/wiki/ISCSI). iSCSI connects to host servers using ethernet (thats why you would use switches for best redundancy and ease of cabling). You would be using the Gigabit ethernet ports on your server to connect to the iSCSI ports of the MD3000i. You do NOT need SAS cables for this.

-Mohan

Thanks Mohan :)

And this is the standard way of doing it? Im sure I read on the vmware forum that using a HBA gave much better performance (although unless using ethernet is going to noticably make things slow then I dont really care too much about performance)

 

Thanks

thanks for the reply :)

I had seen people mentioning these iSCSI switches but I have to say I didnt realise what they were really for. So even though my servers will be right next to my SAN I still need to have these iSCSI switches yeah? If the Powerconnect 2708 is just a regular gigabit ethernet switch then whats the difference between plugging my server and my MD3000i into this as opposed to just connecting both of the servers directly to the MD3000i? (sorry if thats a stupid question!)

 If I do NEED these switches then is it just normal ethernet cables that I stick into each end or do they need to be something special for the iSCSI side of things?

Oh and yeah its the single controller MD3000i we are looking at

 

Also, just to clarify - you are saying we dont need anything extra in the servers other than making sure we have enough gigabit ethernet ports yeah? I had read that this could perhaps cause a lot more processor power to be used when compared to using a HBA but the problem is I dont know where on earth I can find a suitable HBA for this situation even if I did want to go down that route (because as you said, the SAS HBA is not for this)

 

Thanks

Chris

To answer part of your question

you only need a switch for ease of cabling and to connect to more than two hosts.

Each MD3000i has 2 iSCSI ports and 1 management port. The system can be managed in-band through the iSCSI ports but it might be easier to set it up through the management port.

You can directly connect cables from one NIC of each server to one iSCSI port of the MD3000i and connect to 2 servers in all. However, you will only have a single connection from the server to the box and hence, no multi-pathing. Multi-pathing will give you a little better performance and slightly better redundancy. But given that you have a single controller setup... just direct connect might be enough.

-Mohan.

SAS HBAs are for the MD3000, not the MD3000i.

 

If you are looking into a single controller MD3000i, I'd recommend a Powerconnect 5424 that you can dedicate to the iSCSI traffic.

If you're going with dual raid controllers I'd recommend 2 of those switches.

If you need to go on a really tight budget, you could consider Powerconnect 2708 switches in their place (8 port Gbit switch). This isn't as good a performance, but it's much cheaper.

 

You then set up 1 switch with:

- 1 cable from iSCSI port 0 on each controller in the MD3000i

- 1 cable from each server (NIC that you'll dedicate to this iSCSI switch)

 

Then for the other switch you use iSCSI port 1 on each controller and another NIC from each server.

 

Each switch needs it's own subnet (Dell defaults on 192.168.130.x and 192.168.131.x, but you can use any 2 subnets you want that aren't used elsewhere in your network).

 

The management ports on the MD3000i need to be connected to your regular LAN.

 

Each server should have at least 3 NIC ports (I'd recommend 4 or more); 2 for the 2 iSCSI networks and then at least 1 for the virtual machine and management traffic (2 or more highly recommended for loadbalancing and failover).

Yes, this is the standard way.   Most all of us ESX users, just use the ESX iSCSI software Iniator with normal 1GB nics.

 

If you have two or more hosts attached?  I'd highly suggest two cheapo unmanaged gig ethernet switches minimum, dedicated to the iSCSI traffic with no ocnnection to the lan at all.   Even two ESX hosts get weird without the switches.   The two switches actually give you 4 redundant paths to your SAN(s) from only using two nic cards on the host as well.   Sort of a neato trick there.  :)

 

If your somewhat new to ESX and SANs?  Try not to worry, the stuff performs amazingly well.   I mean, we virtualized some whopper doozy physical servers. 24 in all.  Users reported performance increases from Physical servers with DAS.