MSA2012i - Redundancy and bandwidth

[Alessandro_78]

Hi all,
in the MSA2012i the four GbE ports will be used simultanously or just only one controller per times?

I'm asking this becouse I'm valuating the overall performance for the MSA but I don't understand if I'll have a 4gbit SAN connection or only 1 or 2 gbit..

Thanks in advance.

[John Kufrovich]

Alessandro,

There are two GbE ports per Controller.

Controller A A0 and A1
Controller B B0 and B1

A0 and B0 need to be on the same subnet
A1 and B1 need to be on the same subnet

Example, Controller A owns the LUN, if you setup iscsi initiator for Round Robin load balancing, Both server nics and ports on Controller A will be Active.

jk

[Alessandro_78]

Is not possible to balance over the two controller having 4gbit bandwidth?

2gbit is too slow.
I need to use it as a shared storage for some VirtualMachine and some mail servers but with 2gbit is impossible.

For example, using 10 SATA disks i'll archive more or less 1500MB of througput that is 12Gbit.

[John Kufrovich]

It depends on how you create a VDISK and volumes. When you create your first VDISK, it is assigned to controller A and all volumes associated with the VDISK run off of Controller A.
If you create a second VDisk and volumes it will be created on Controller B.

You can then balance the IO between the two controllers.

[Alessandro_78]

Ok, but one server will access to one volume on one controller per times.
So maximum bandwidth for one server to one volume di 2gbit.

And if that controller fails? Volume will be switched over the other controller automatically?

[John Kufrovich]

Correct, if the controller A fails, VDISK/Volumes will move to controller B.

If you want to test it. Don't pull Controller A. Start some IO to your volume.
Just go to the SMU interface and perform shutdown on controller A. You will see a pause in the IO, because ownership changes and then IO will resume.


jk

[Alessandro_78]

Actually I haven't a san to perform these tests.

I'm asking so because i want to virtualize some servers but I think that 2gbit are too slow.

[Patrick Terlisten]

Hello,

mmmhh... I don't think that it will be to slow. Your bottleneck will be the disk performance. More disks, more performance. You can load balance the load between the controller with the logical drive assignment to the controllers. If you think that 2 GBit Ethernet is too slow, buy an EVA with 4 GB FC and the matching FC infrastructure.

How many guest will you use? How many disks will be in the MSA?

Best regards,
Patrick

[Alessandro_78]

I would like to put more or less 50 guests in more or less 4-5 servers.

I think that with 6 SATA disk in Raid1 i'll archieve a thoughtput of 450mbit that are 3600mbit that are more than the maximum performances that a single controller can goes.

[John Kufrovich]

Alessandro,

4500mbit = 56MB/s performance.

You need to look at your application transfer block size. Example, most backup apps are either 64k or 128k. Most copies are 64k. Depending on version of exchange, 4k-64k. So you can see there is some variation.

If you are concerned about the controllers performance, why use SATA. The SAS drives are more capable of handling IO than SATA.

BTW, I just happen to have my system up and running in the lab with a 6 disk raid 1. Using IOmeter, I'm able to acheive ~90MB/s. I'm sure I could squeeze out a little more.

If you feel that's still not enough you could look into the enhanced version of the MSA2012FC.