Flash memory storage is helping some IT pros provide enough performance to virtualize tier-one applications, though...
the technology is still seen as too costly.
The drawback is always going to be cost.
-Bill Hill, infrastructure IT lead for a Portland-based logistics company
“The reason we went to virtualization -- consolidation -- bit us in the last year,” said Walt Thinfen, vice president and chief information officer for document-scanning firm Visioneer, Inc. The company has about 200 servers that were virtualized using VMware vSphere on four physical hosts.
The first problem that cropped up was that it became impossible to do nightly backups because of I/O contention on the firm’s conventional EMC Corp. and NetApp Inc. storage area network (SAN) storage.
“It wasn’t unusual for me to have only one solid backup over the course of five to seven days,” Thinfen said.
In production, high-performance applications such as SAP, which in Thinfen’s environment is running on an Oracle 10 back-end database, were also timing out due to I/O contention. SAP order creation “should take milliseconds, but in some cases it was taking five to seven minutes… it was beginning to impact our ability to take orders and deliver shipments to our customers,” he said.
Rather than buying more physical servers, more physical storage or bringing the tier-one apps back to physical servers, about three months ago, Thinfen brought in a flash-based storage appliance from Astute Networks. SAP, Exchange and a self-service portal now run on the Astute Networks box.
Astute claims it can deliver 80,000 input/output operations per second (IOPS) for read operations and 50,000 IOPS for writes. Operations were most impacted when contention was highest -- when European operations came online in the morning while U.S.-based systems were backing up.
“I don’t know if we’re at 80,000 IOPS, but we’re close to that number,” Thinfen said.
Other users opt to add Flash-based storage to boost overall performance of traditional SANs.
“We’re virtualizing a lot of tier-one applications, and performance of those applications is becoming more and more important to the business,” said Bill Hill, infrastructure IT lead for a Portland-based logistics company. Such applications in Hill’s environment include Exchange Server, SharePoint, Active Directory domain controllers, as well as Oracle’s E-Business suite.
The company’s Oracle databases typically require between 500 and 700 IOPS, but its existing EMC Celerra array can deliver about 3,000 IOPS total.
“Storage is abundant. But [with] capacity for I/O operations, we’re hitting a ceiling,” Hill said. “As a result we have people saying Oracle isn’t performing as well as it did when it was running on dedicated hardware.”
Playing hybrid-storage approach for advantage
To keep up with performance demands, the company is bringing in a new EMC VNX disk array to replace the Celerra array. The new VNX comes with five flash drives for caching. Though it amounts to just 100 GB usable space, Hill said he expects the new array to deliver between 6,000 and 8,000 IOPS. The advantage to the hybrid approach, as opposed to a separate flash array like Astute Networks’ product, is that the cache will speed performance for all the virtual machines running on the SAN. In particular, it can make sense to attach Oracle applications to solid-state drives (SSDs) when virtualizing.
One client’s move last year from Fibre Channel disk drives to SSDs to support a hybrid online transaction processing (OLTP) server used for both day-to-day enterprise resource planning and for reporting using Oracle Discoverer, recouped big returns, said Jay Weinshenker, owner of Weinshenker Consulting, Austin, Texas. They “saw latency drop to near zero and reports finish anywhere from two to 10 times faster,” he said.
SSD cost remains a hurdle
Even those who use SSDs say price is still an issue. Astute, for example, charges $29,000 for 1.2 TB capacity.
“We need to have bigger storage [capacity] for less money,” Thinfen said. “I’d like to see [SSD storage] available at a five, 10, 15 or 20 terabyte clip.”
In general, flash SSDs cost about $1.20 to $2 per gigabyte, while traditional hard disk drives cost about four or five cents per gigabyte.
“The drawback is always going to be cost,” Hill said.
This cost equation means some users avoid the technology altogether. Lance Madsen, a systems administrator for InnerVision Advanced Medical Imaging, said he wishes he could use SSDs in his virtual environment, and uses Flash storage in his home computers. But, the technology is “still too cost prohibitive for enterprise storage, though it may be something I consider for our virtual desktops next year if I see too large of a [performance] impact on our current SAN when we deploy.”
Beth Pariseau is a senior news writer for SearchServerVirtualization.com. Write to her at firstname.lastname@example.org.