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The University of Greenwich School of Computing & Mathematical Sciences has replaced its Hitachi Data Systems (HDS) SAN with Nexenta storage software on commodity hardware and reaped savings of around 20% compared to the cost of mainstream storage supplier hardware.
The school – which has around 5,000 students on- and off-site, plus staff and researchers that use Web apps, Oracle databases, email and office productivity apps – first deployed Nexenta storage software in a pilot project about three years ago.
Staff and students had been reporting very long login times – up to five to 10 minutes – to the school’s IT systems, which were then supported by an HDS AMS2100 SAN, said Frank Razaghzadeh, head of support at the school.
“The HDS SAN was a reliable system but couldn’t cope with login traffic. The big problem was long response times from the storage, which made access slow at peak times when students were logging on and downloading profiles.”
Working with reseller Thames Valley-based reseller NAS UK and partner Staffordshire-based Stone, the school installed a small Nexenta solution as a pilot to accelerate the HDS storage array. It comprised a SuperMicro server with STEC SSDs for caching. It was connected via fibre channel to the HDS array and took a LUN to serve user profile data. This hardware was later repurposed as the secondary on-campus cluster.
After this went live and was shown to accelerate response times, the school added further Nexenta storage comprising two head appliances with SAS drives and some flash SSD.
This platform took over the file-serving requirements previously provided by four separate file servers, which were then decommissioned as well as the profile serving that had been handled by the first Nexenta system.
The current Nexenta configuration comprises five SuperMicro servers running two Nexenta high availability clusters plus a single Nexenta node. The servers run a variety of Intel CPUs and varying amounts of RAM from 24Gb to 196GB. Drives in use range from 450GB up to 2TB and from nearline to 15,000rpm plus STEC flash SSDs of between 8GB and 400GB.
The HDS SAN was retained for bulk storage and a NetApp FAS 3140 provides storage for VDI files and data but a full migration to Nexenta is planned for the coming summer. It all runs on a mixture of 4Gbps fibre channel and 1Gbps Ethernet.
Nexenta’s storage software is based on the open source ZFS, designed by Sun Microsystems. It is a fully featured storage file system and OS with synchronous and asynchronous replication, high availability, snapshots, cloning, thin provisioning and data deduplication.
The storage market is dominated by suppliers that sell hardware bundled with their own controller software and operating systems (OS). Software-only products aim to break that link by offering storage software that can be deployed on commodity servers with standard disk drives, cutting costs in the process.
So, what were the benefits of moving from traditional hardware array products to storage software on commodity components?
Razaghzadeh said: “Storage software is less costly and you’re not tied to any one vendor. We didn’t want to reduce cost if we weren’t going to get the performance, but we got good responses to the Nexenta pilot from students, and that’s our key performance indicator (KPI). With HDS we were getting 30% of students saying they suffered slow logins. Now that number is zero.
“We can use any disk; cheap disk off the shelf and don’t have to buy NetApp- or HDS-approved HDDs. The difference in price is £300 to £400, compared with £500 or £600.”
Razaghzadeh also said the school had benefited from dealing with smaller suppliers. He said: “We didn’t get the support we expected from one of the bigger vendors; they said we were a small fish in a big pond. Nexenta and NAS UK gave good service. They’re new to the education sector and wanted to make a mark.”