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Storage Virtualization | FAQs & Discussions How To Build A Low-Cost High-Performance iSCSI SAN using an IBM System x (xSeries) Server In this example, we will configure a high-performance iSCSI SAN using an IBM System x (xSeries) server. The objective is to build a scalable storage array with at least 2TB of storage and 2 iSCSI ports for under $15,000. The configuration should allow room for growth in capacity and/or features. Date of this configuration: October 21, 2006. The following server was configured using IBM's AM configurator version 10.19, a system configuration tool available on the IBM public website. We choose a low-cost IBM x3500 tower server like those typically found in small office environments. It can be converted to a 5U rack model if required. We configure the server with a single dual-core Intel Xeon 5130 processor. The x3500 can support up to two processors, but as our iSCSI SAN is not overly CPU intensive, the CPU will not present a bottleneck. The x3500 comes with 1GB of RAM standard. We add in an additional 2 GB of RAM bringing the total to 3GB of RAM, most of which will be appropriated by our SAN software to be used as Storage Server cache. The x3500 has a total of 12 memory slots, of which we have only used 4, so there is plenty of room for additional cache. We load up all internal disk slots with 8 internal 300GB SAS drives to be used as SAN storage. We'll use a ServeRAID-8k SAS RAID controller in place of the integrated controller, allowing us to configure the drives in RAID-5 for improved data protection. With RAID-5 on 8 x 300GB drives, this will yield approximately 2.1TB of usable SAN storage. We'll partition the RAID group with the controller to give us a small OS partition, and the rest we'll use in Virtual Storage Pools for our SAN.

The IBM System x3500 This xSeries model includes integrated dual 1Gb Ethernet ports. These two Gig-E ports will be used as front-end iSCSI SAN ports or "targets" that publish the virtual storage (aka volumes or LUNs).

As this is in effect a Single Storage Processor SAN, we should take measures to ensure availability. We'll use the SAS RAID controller to protect against individual disk failure. We'll also add in a redundant power supply and fan. I would recommend installing a UPS as well.

Note that the x3500 tower server includes 6 PCI slots (including 3 PCI-Express, 2 PCI-X, and 1 PCI) available for expansion, so we have plenty of room to add additional HBA's for capacity expansion (external storage) and / or additional iSCSI or Fibre Channel targets as our future needs require.

How to turn the IBM x3500 server into an iSCSI SAN Storage Array

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 IBM x3500 into a high-performance iSCSI SAN.

The software configuration consists of the SANmelody™ Storage Virtualization software package with the optional Auto Provisioning feature. The Auto Provisioning feature radically simplifies storage allocation and SAN management by creating an abstraction layer between our physical storage (the 8 SAS drives in the x3500) and the virtual SAN volumes we will offer our client Application Servers. With Auto Provisioning, we will place the volumes from our SAS RAID controller in Storage Pools from which our SAN volumes can be drawn with a simple "right-click".

The SANmelody™ Storage Virtualization software runs on top of a Windows XP Pro or Windows 2003 Server platform. As we are currently using 3GB of RAM in the server, XP Pro will suit our needs.

We will install XP Pro on our x3500 and then install the SANmelody™ software using its familiar, intuitive wizard. Then we will follow the easy to read, illustrated built-in online help guide to begin using our iSCSI SAN storage server.

As of this publication, DataCore has a limited-time SANmelody™ Virtual Infrastruture Foundation promotion which includes just the software we need.

Advantages of this Solution Over a NetApp StoreVault S500 Appliance

Taking the SANmelody™ software approach to developing a SAN virtual infrastructure has numerous advantages over the low-cost appliance approach. Comparing, for example, the NetApp StoreVault S500 SAN/NAS appliance with our x3500 / SANmelody™ configuration, several benefits are evident.

• SANmelody™ runs on a standard, familiar Windows OS platform; the entire SAN management is a standard Microsoft Management Console (MMC) plug-in. If you can manage a Windows server, you can manage a SANmelody™ SAN. The NetApp box is based on their proprietary Data ONTAP OS SVE and StoreVault Manager — yet another thing for your admins to learn.
• Higher performance. Our SANmelody™ configuration has 3GB of cache. The NetApp StoreVault S500 is limited to 1GB. Notice also that the NetApp StoreVault S500 implements RAID in software. In our configuration, we are using a hardware RAID controller. Finally, the NetApp StoreVault S500 uses SATA-II drives, compared to our high-performance SAS 10K RPM drives.
• The NetApp StoreVault S500 is limited to 2 Gig-E Network Ports which are used for both iSCSI targets, file sharing (NAS) and the management interface. You can also add an optional Ultra160 SCSI card, presumably for tape backup. Alternatively, you can add an optional Fibre Channel card. Our SANmelody™ server comes with 2 Gig-E ports, but there are 6 additional PCI slots available for expansion: we can add additional iSCSI targets (NIC cards), multi-port Fibre Channel HBAs, Ultra160 and Ultra320 cards, not to mention additional RAID controllers for SAS, SATA, and Ultra320 SCSI capacity expansion.
• Our SANmelody™ configuration can scale to hundreds of drives: several PCI slots available for adding additional RAID controllers. The NetApp StoreVault S500 has a maximum capacity of 6TB, 12 drives.
• Any type of drive supported: SATA, SAS, Ultra320 SCSI, Fibre Channel, FireWire, USB2... any drive that can be seen in the Windows Disk Management screen of the Microsoft Management Console. The NetApp StoreVault S500 is limited to SATA-II drives.
• You can use any RAID level that is supported by the RAID controllers — the ServeRAID controller we have chosen for our internal storage offers RAID-0, 1, 5, 10. With the NetApp StoreVault S500, you are limited to their software-based RAID-4 and RAID-DP.
• Support for unlimited LUNs — the NetApp StoreVault S500 is limited to 32 LUNs. SANmelody™ will allow you to create as many volumes (LUNs) and application servers as you wish.
• Additional SANmelody™ software license key features can be turned on to implement Extreme High Availability, Remote Replication, and Snapshots. Upgrading the SANmelody™ software is a simple license key upgrade that does not require downtime. SANmelody™ is truly scalable and will grow as our needs grow.
• Truly modular: the software is in not bound to the server hardware or server vendor. If you are an IBM shop, you'll appreciate that this SANmelody™ server integrates into your shop as just another IBM System x server running Windows XP Pro.

This last point is particularly important. Although the S500 and our SANmelody™ / x3500 configuration have similar entry price points, the S500 appliance features "built-in obsolescence"; SANmelody™ software will keep its value long after the S500 is end-of-life.

A few years down the road as server platforms continue to evolve, and as the x3500 has come to end-of-life, we can transfer our SANmelody™ software to a newer, more powerful server. As new disk technologies come to market, our SANmelody™ server will be ready to take advantage of them. As new features are introduced in SANmelody™, support-paying customers will get the upgrades for free.

On the other hand, the appliance approach limits you to the feature set and technologies available at the time of purchase. A NetApp StoreVault S500 you purchase today won't be able to use new drive technologies — it's limited to SATA-II. And when the first three years of support have run out and you get the support renewal bill, it will be time to forklift the NetApp and replace it with something else. You'll have to buy the entire feature set all over again.

One last note — As we're comparing our SANmelody™ configuration to the NetApp StoreVault S500, it's worth noting that the S500 also has a built-in "NAS" or File Sharing feature, supporting both NFS and CIFS protocols. The value of combining NAS and SAN functions in the small S500 appliance (with only 1GB RAM, and also implementing software RAID) is questionable; this is likely to be a performance bottleneck, as the file system functions of NAS will make significant demands on our cache. Nonetheless, as SANmelody™ runs on a standard Windows OS platform, our SAN server can also double as a NAS server: You can easily configure Windows shares from virtualized SANmelody™ volumes using standard Windows file sharing.

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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