HP SAS HBA with IBM Storage and SAS SAN Vs. iSCSI SAN

[WarlockArg]

Hi, I'm working on a proyect and I have to add a SAN solution to my customer infaestructure. My customer already have a HP Server and we I wanted to add another server, but an IBM one. I thought adding an IBM storage (DS3200) that has two SAS interfaces. The problem is that the IBM distribuitor says that doesn't know if the HP server will be able to communicate with the IBM SAS Storage. So, one possibility was to put in the HP Server an HP SAS HBA Controller. The second option is putting an IBM SAS HBA Controller. I think because SAS is an standard, that it doesn't matter what brand I use of HBA. Shouldn't it work anyway?

There's another option that is adding an iSCSI storage instead of SAS one. The problem is I don't know the performance that the iSCSI storage have. What I want to put inside it is VM with Exchange Server (50 mailbox), an ERP (for 50 users) with it's SQL Server, a VM File Server, a VM with Active Directory.

So, the questions are:

1- Does anybody have experience with iSCSI storage in order to see if its performance if goog enough (I'm planning to use a dedicated gigabit switch for the iSCSI network)?

2- Does anybody know if I can use different brands of servers (in this example one IBM and one HP) with a IBM SAS Storage? Has anybody already done it? Are the HP SAS HBA compatible with IBM iSCSI storage? Are the IBM SAS HBA compatible with HP Servers?

3- In case of being able to do what I say in question 2, what do you suggest? To put a HP SAS HBA inside the HP Server or to put an IBM SAS HBA inside de HP Server?

Of course the option I would like to use is adding an IBM SAS Storage instead of using an iSCSI one, but I'm not sure of their compatibilty between HP Servers and IBM storage.

Thanks in advanced.

[mike_laspina]

Hi,

SAS is just another protocol like FC DAS etc. As long as the target complies to a spec that the initiator understands and VMware supports the initiator and target your OK. I would not use SAS for this application.

iSCSI will handle that load very easily, what you need to be concerned about is the amount of IO load. Two or three servers and 50 users is very small. I have 25 servers running on 1 ESX host in development running over 2 x 1GB QLA4050c cards. No issues at all.

Regards,

Mike

vExpert 2009

[WarlockArg]

Mike, I really appreciate your answer. One question about it. Why do you say you would use for this case an iSCSI storage? Is there any case that iSCSI storages have better performance than SAS ones?

I always thought the best-performanced storage were FC onos, second the SAS ones and in the end, the iSCSI ones. I thought the SAS storage had more bandwidth than iSCSI storage and they supported more I/O per second than iSCSI. Also I thought that people chose iSCSI because its price it's lower. Am I wrong?

Thanks again.

Guido.

[mike_laspina · Accepted solution]

The reason I would not use SAS in this case is your application does not require that level of performance and the cost in not justified. You can provision iSCSI and direct the cost saving into more important features like snapshot, dedup and replication. If you were to provision this solution with the DS3200 you would spend 10K and have none of those features. Performance will be very good but you will find the system is not even warmed up with that load. The SAS protocol can sustain high IO but thats not the what provisions IO, it's the number of disks and the RAID mode that defines your IO capability. I have benched 40K small IOPS over a single 1GB iSCSI cached target, thus it can do significant IO. Throughput is not as high but do you really need it. In the future you can cost effectively move to 10Gbe if you find the bandwidth to be insufficient, that would run 3+ times faster than the 3GB SAS limit which is not cost effective to upgrade.

Regards,

Mike

vExpert 2009

[WarlockArg]

Fantastic answer!!! Thanks Mike.

Guido.

[margol]

Mike, thanks for the answer.  As a relative newbie to enterprise storage, this helped me get past the first "Aha!" moment of ther real difference between a dedicated HBA bus vs shared iSCSI ethernet "bus".