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MSA500 clustering & high availability

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MSA500 clustering & high availability

I'm trying to help support a customer that is using an MSA500. Unfortunatly, the customer is in another state, and I've never touched one of the units. Therefore, I'm not in exactly the best position to help customer, but I'm doing what I can.

Goal: To have a RAID 1 (mirror) configuration with access to the same data from two servers.

The customer has purchased a second G2 controller. Each G2 has two ports. I believe that perhaps the customer should have purchased the high-availability kit. But, that looks like it is designed primarily to allow one server to have two paths of access to the data. We want two servers to each have one path to data.

It appears the customer has it currenly configured to where one server sees some of the drives, while the other server sees the other drives. As noted, we want both servers to see the same drives. Do they need the high availability kit and/or the multipath software to accomplish this? Or do they have everything they need and simply don't have it configured correctly? Thanks.
16 REPLIES
Greg Carlson
Honored Contributor

Re: MSA500 clustering & high availability

Paul,

What you are describing is not at the hardware level. You could present the same logical drive on the MSA to both systems. You will corrupt the data almost immediately as you will have two different systems writing to the disk at the same time in the same space. You need a third party solution to achieve what you are looking for.


Polyserve has a solution that you are looking for. http://www.polyserve.com/

Ciao,
Greg
Lets Roll!

Re: MSA500 clustering & high availability

Thanks for responding. Perhaps I was not clear. The two computers have internal boot drives. The MSA500 is used to hold a database. The two computers have software to make one "hot" and one "standby". So, only one computer will be writting to the hard disks at one time. However, should one computer fail, the other one will take over.

We have used the MSA1000, a Fibre-Channel solution product for this purpose before. This is just the first time that we have tried to use the MSA500--as far as I know.

I had thought that the dual port capability of the G2 would provide this by itself. I think the customer may have simply not configured it correctly. As it is, the two ports are not seeing the same drives. I think the customer is simply not configuring it correctly.
Greg Carlson
Honored Contributor

Re: MSA500 clustering & high availability

Paul,

The two servers need to be in a clustered configuration. Then one node would be active and one standby. Cluster service manages who can talk to the shared logical drive on the MSA.

Ciao,
Greg
Lets Roll!

Re: MSA500 clustering & high availability

Thanks again for responding.

When you say the nodes need to be in a "cluster configuration", the question is, what does the customer need to implement a "custer configuration"? Does that require the High Availability kit?

You had suggested a third party product, but I do not think this is necessary. Our database *already* has hot/standy capability built in. It will *already* insure that only one computer is reading and writing to the RAID. We do this type of thing a lot, we just haven't used the MSA500. All I need to do is to be able to see the same disk array from two different ports. I would think the G2 would do this already, without needing anything else at all. I wouldn't even think that I would need the High-Availability kit, but I could be wrong.

I guess I'm just not understanding why the customer reports not seeing the same thing from the two ports.
Greg Carlson
Honored Contributor

Re: MSA500 clustering & high availability

Paul,

The third party product I had mentioned at first was for having two standalone active systems sharing the same logical drive. You don't have that scenario. If you already have standby and active mode available, what you need to verify is SSP. On the MSA1000, for a cluster you need to present LD X to both HBA's and the same would apply to the MSA500.

Is SSP enabled?

Ciao,
Greg
Lets Roll!

Re: MSA500 clustering & high availability

Ah, now we are getting somewhere. I guess I should have mentioned one thing: Other people at my company have used the 1000. I've never used it either.

And while HP's site has specifications, they don't have the complete manual to download. Or at least I couldn't find it. So, I don't know what "SSP" is. But, I can ask the customer.

Re: MSA500 clustering & high availability

Okay, now that you've given me the clue of SSP, I did a search on it, and found it is "Selective Storage Presentation" which I believe is for configuring a cluster. Sorry for being so ignorant. Probably, with this clue, the customer can figure out what he needs to do to configure the G2 for clustering. Thanks.
Greg Carlson
Honored Contributor

Re: MSA500 clustering & high availability

Paul,

SSP is "Selective Storage Presentation" In the ACU, highlight the Array controller, on the right hand side you should see Selective storage presentation. If it is enabled, only the operating system for the HBA which is presented to LD0 will see that. Go into the ACU and enable SSP for the second array controller, then you will see the same logical drive.

Ciao,
Greg
Lets Roll!
Greg Carlson
Honored Contributor
Solution

Re: MSA500 clustering & high availability

Once you enable the second controller, both systems will see your logical drive.

Cheers,
Greg
Lets Roll!

Re: MSA500 clustering & high availability

I'll give this information to my customer. If he gets it to work, and I suspect he will, I will come back and give you 10 points for your answer.
Uwe Zessin
Honored Contributor

Re: MSA500 clustering & high availability

The term 'Selective Storage Presentation' was mostly used in the Digital/Compaq world. Others call it 'LUN masking'. The effect is the same ;-)
.

Re: MSA500 clustering & high availability

Okay, the customer configured SSP, and it is now working. Thanks for the help. That is exactly what we needed!
Greg Carlson
Honored Contributor

Re: MSA500 clustering & high availability

Good news Paul.

And just in time to enjoy the weekend.

Cheers,
Greg
Lets Roll!
akki_1
Occasional Visitor

Re: MSA500 clustering & high availability

Hi Friends,

I was also going through ebooks on clustering and high availability, I wanted to implement 2 node cluster and understand various clustering technologies like heartbeat,OCFS,GFS,database replication and clustering of mysql etc. I got a very good ebook on clustering explaining everything from scratch on http://www.ebooksyours.com/what-is-clustering.html

Thanks,
Akki

Re: MSA500 clustering & high availability

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Re: MSA500 clustering & high availability

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