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Storage Virtualization | FAQs & Discussions How To Build A Low-Cost Scalable iSCSI SAN using HP DL-320s Servers and MSA-60 Disk Enclosures Author: Tim Warden The text of this example comes from an email and discussion I had with a customer looking to move forward with a Server and Storage Virtualization project. The customer's shop is all HP servers. He had some concerns about which hardware he should choose for building the storage server. Date of this configuration: March 7, 2007. Hello Gary, As we discussed, I've put together an example config of using HP kit to build a one-vendor solution using DataCore. The idea here is that you will be using HP hardware for servers, storage, etc. The storage management or storage controller becomes an application running on a standard HP platform. You could use just about any HP server and disk solution you choose — I just picked what looked like an attractive package for maximizing storage in a small footprint. To that end, I'm using an HP DL-320s, which has 12 internal SAS/SATA slots, for up to 12 x 750GB SATA drives or 9TB raw in a 2U enclosure. This server has 2 built-in Gig-E ports and also has 2 PCI-Express slots, an x8 and an x1, both are x8 connectors. In my configuration, I've got a standard dual-core CPU, with 4GB of RAM which SANmelody will use as storage controller cache. I've added 2 x 80GB drives, which you can run in RAID-1 for your boot drive (partition it, put the system in a small 8 or 12 GB partition, save the rest of the space for SANmelody storage or for replication buffer space should you ever decide you want to implement DR.) Then I added 10 x 500GB SATA drives, giving you 5TB raw.

Please note, there are many different ways you can configure the storage. Maybe you would prefer to start smaller to reduce costs, using fewer disks, or smaller capacity disks, or SAS disks. Or you can stripe them differently: instead of the two 80GB drives in RAID-1, you could just as easily only configure 500GB drives, and use the P800 to Auto-Carve the RAID groups to give you your boot partition and partitions for use by SANmelody's Thin Provisioning Pools. That's probably what I personally would do, but I went the 2 * 80GB boot drive route to help you see building a SAN storage array is just a matter of picking your favorite server and direct attached storage and then loading an application on it to use the DAS — in this case the application is SANmelody.

I've selected a P800 SAS RAID controller which will plug into the PCIe x8 connector. It's a high-performance card and will attach the 12 internal drives on its internal ports via 2 backplanes in the DL320. It has 2 external SAS ports which can connect external SAS expansion chassis. (More on that later.)

Finally, and optionally, I've added a dual-port GigE card. It's a PCIe x4 card that can be installed in the PCIe x1 slot (which has an x8 connector). The card is optional: I just added it here just to demonstrate how you can indeed add add'l iSCSI ports on each SANmelody head by adding in a NIC. The card is cheap ($260) and would add an additional 2 GigE ports. HP also has a similar model at $280 that includes an offload engine.

So we have configured our SAN hardware. The thing that's missing is the intelligence to turn this ordinary high-power server into a SAN: the SAN volume, caching, and LUN masking management, as well as the iSCSI target drivers to make the 2 Ethernet ports behave like an iSCSI storage array's ports. For this functionality we will use a unique software package from DataCore Software Corporation called SANmelody™. This software will turn the ProLiant into a high-performance iSCSI SAN.

Storage Expansion with the MSA-60 and P800 RAID Controller

Now, if you need additional storage, you can add any of HP's MSA enclosures in a Direct Attached fashion. I've included a second quote from the HP online store for an MSA-60. This unit will hold 12 SATA and/or SAS drives and connects to the P800 controller. You can attach up to 8 enclosures to the P800, for up to 96 x 750GB SATA drives = 72TB. I doubt you'll be needing that much in the next two years, but as you can see, you can scale this configuration.

Advantages of this Solution Over a "Storage Appliance" from NetApp, EqualLogic, etc.

• This SAN storage solution uses all HP hardware: the same vendor you are currently using in your shop
• Less expensive, particularly when you start to scale
• Higher performance with more cache. And the cache is standard RAM, easily upgraded to 8GB.
• Can scale to hundreds of drives: the P800 can support a large number of drives in MSA-60 or MSA-70 shelves
• SANmelody supports ANY type of drive: SATA, SAS, Ultra320 SCSI, Fibre Channel, FireWire, USB2, etc. If you can discover it in Windows Disk Management, SANmelody can use it.
• Support for many OS platforms (VMWare ESX, Windows 2000, 2003, XP, Solaris, Red Hat, SuSE, HP/UX, MacOS)
• Support for unlimited LUNs
• Support for unlimited servers
• Software license key features can be turned on to implement Synchronous Data Mirroring (for Business Continuance), Snapshots, Fibre Channel, and Thin Provisioning (DataCore invented it back in 2000, in spite of other vendor's claims...)
• Asynchronous Replication can be implemented by turning on a license key. You can replicate volumes to or from this SANmelody server to any other SANmelody or SANsymphony server.
  [Read my paper about Replication and DR]
• Truly modular: the software is in not bound to the server hardware or vendor. You can install the software on any HP Proliant, IBM System x, Dell PowerEdge server, or "White Box".

Implementing Business Continuity

For Implementing Business Continuity, you'll need two of these boxes, each running SANmelody C with its Auto-Failover option. That will give you the ultimate resiliency against failures. No internal drive failure, failed GBIC, LIP Storm or Voltage Regulator or Backplane problem could bring down your SAN storage. You could yank the power on one of the SANmelody's and your ESX servers will fail to the surviving SANmelody. Physically separating the two into different racks and on different power rails will assure that nothing short of total site failure will stop production.

You'll need a Cat 5e or Cat 6 Crossover between one Gig-E port on each of the DL320's: that will be used as a Mirror Channel for implementing Synchronous Data Mirroring between the two boxes. I use a Cat 5e here in my lab — works fine. SANmelody will use iSCSI over the crossover to implement the mirroring of writes. You'll configure those two ports in a private network. I use a 10.0.0.0 (Class A) network for that and a std. Class C for my SAN traffic to the ESX servers.

So you'll have two active storage processors, each with 4GB of cache, each with an front-facing iSCSI port (or 3 if you add in the extra dual-port NIC card), each with its own internal storage, and Extreme High Availability via synchronous data mirroring.

You can further isolate the two SANmelody servers in different buildings, or across campus using iSCSI or Fibre Channel to synchronously mirror them. Add generators at each site, and you've effectively created an extremely highly available configuration that can withstand the complete loss of one of the buildings.

Please don't hesitate to call if you have any questions about this, or if you'd rather see a config using, say, a DL-385, MSA-20, MSA-70, etc.

Best regards,

Tim

Las Solanas Consulting is not a DataCore or HP reseller. This article is published for informational purposes. However, you can purchase this software from the DataCore website or contact DataCore™ or a DataCore reseller for sales information.

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