Over the past few years, unified storage systems have been gaining mindshare among UK businesses. They’re increasingly being used to handle storage challenges such as the need for block-access storage for transactional databases and the sustained growth of unstructured data, such as end users' files on Windows shares.
Performance-oriented storage has traditionally been run on Fibre Channel SANs, with everything else stored on NAS and accessed via NFS/CIFS. More recently, iSCSI arrived and gave block access at lower costs than Fibre Channel. Vendors spotted the opportunity to combine all protocols in a single piece of hardware, and customers are more and more taking the opportunity to gain the advantages of such unified storage systems.
Before unified storage systems, when storage was either NAS, Fibre Channel SAN or iSCSI SAN, space on one array could not be consumed by the others, or at least not easily (although the addition of a NAS gateway providing a connection between the Ethernet network and the SAN delivers a unified view over multiple storage types). This meant poor utilisation, management overheads and data that didn’t necessarily reside on the most cost-suitable disk type. With unified storage systems, there’s now a choice of protocols in one hardware product, with greater flexibility, lower costs and easier manageability. To investigate how unified storage systems are being used in UK data centres, we spoke with two IT organisations, one a large IT services company and the other the company that handles the London Overground’s network.
Quostar picks Dot Hill Fibre Channel/iSCSI
Quostar is a Dorset-based IT consultancy focused on delivering cloud and outsourced IT services; it has three data centre locations and about 500 TB under its command.
The company stores the bulk of its own and its customers’ data on Dell PowerVault MD3000i iSCSI storage arrays, which house SAS and SATA disks. However, according to Managing Director Robert Rutherford, Quostar has taken its first steps toward unified storage systems.
"We started with cheap iSCSI from Dell, the MD3000i boxes. They have been good and reliable, but performance and scalability have become issues, as well as flexibility," Rutherford said. He looked at a number of solutions, including Dell's EqualLogic range and HP's MSA range.
"We decided not to go for the HP MSA because they were just rebadged Dot Hill boxes," Rutherford said. "We thought we might as well go directly to Dot Hill. We had also heard good things about them from our customers, who said they had no issues, they performed well, and the support was good."
The company also rejected systems using iSCSI over 10 Gbps Ethernet. "There's a lot in the air about which way the market will go, and we had a requirement for the faster 8 Gbps speed," Rutherford said. "But we decided that 10 Gbps Ethernet is too expensive because the price for host bus adapters [HBAs] is still too expensive."
So Quostar bought two Dot Hill 3930 Multiprotocol SAN RAID Systems with 12x 600 GB SAS 15,000 rpm disks, which deliver 7.2 TB SAS in a RAID 10 configuration, accessible either via iSCSI over 1 Gbps Ethernet or over a standard 8 Gbps Fibre Channel link. This allows Quostar to use the iSCSI connection for applications such as replication and remote copying, while the Fibre Channel is reserved for the multiple VMware-hosted virtual servers the company hosts on behalf of its customers. Rutherford said that a key reason for going for unified storage was the ability to interface with his legacy iSCSI systems.
"The Dot Hill boxes are very easy to set up. It takes just 30 minutes, and it's easy to understand, so that side is great," Rutherford said. "You lack some bells and whistles -- the kinds of options you get with enterprise boxes for scalability in terms of storage virtualisation, such as data deduplication and thin provisioning, but they're decent functional boxes."
Rutherford said the only thing that could be improved on the Dot Hill product was performance monitoring. "You can get what you need out of it, [but] it's … a manual process; you need to go to the command line," he said.
The main benefit of a unified storage system for Rutherford is the lack of vendor lock-in. "With this hybrid approach, you have the flexibility of interfacing with different technologies and systems now, and if requirements change there's no lock-in, and you don't pay any more for a hybrid system anyway," he said.
Rutherford said that Quostar will stick to unified storage in the future, with the Dot Hill units effectively being pilots for future purchases. "We will phase out the Dell boxes," said Rutherford. "The problem with them is that you're locked into the boxes; you can't expand them."
London Overground goes for NetApp iSCSI/CIFS
London Overground Railroad Operations Ltd, or LOROL, is the train operating company responsible for running the London Overground network, which it does under a concession agreement with Transport for London; the company is jointly owned by MTR of Hong Kong and Deutsche Bahn of Germany.
Running a railway is a data-intensive business -- the company has more than 13 TB under its command -- but cost containment is of paramount concern. So, what Gareth Murphy, LOROL's head of IT, needed was a storage system that would require minimal management and that would fit into a tight capital expenditure budget. When LOROL was established in 2007 and Murphy was shopping for storage, he was at first convinced he would need Fibre Channel and NAS storage to meet his needs, but he quickly changed his mind on the former after seeing demonstrations of iSCSI.
What he saw in iSCSI was a technology that costs less to buy, and in unified storage systems a way of avoiding the high levels of management overhead that running separate devices would entail. He bought from NetApp on those grounds, and because the company offered a scalable solution.
LOROL considered HP’s Enterprise Virtual Array (HP EVA) but rejected it because, Murphy said, it was much more expensive than the NetApp offering. "We only had six or seven weeks to put it together, so we didn't have the luxury of shopping around. I was pretty impressed with the NetApp," he said.
After acquiring one NetApp FAS 2050, LOROL bought another that proved similarly easy to deploy. Also, because the company was setting up the systems from scratch, it had flexibility to experiment and perform testing before installation.
LOROL uses both of its NetApp devices for all types of storage. "We have two controllers, one for CIFS, the other for iSCSI," Murphy said. He runs the company databases over iSCSI, including Microsoft Exchange; Autonomy Zantaz, an email management and archiving system; SQL Server; Oracle; and a small IBM database. The CIFS protocol and the remaining storage are used for Windows shares.
"We had no challenges with storage," said Murphy. "They said it would all just work, and it did. It was a fairly smooth implementation."