A powerful performance punch is a nice bonus for any company, but sometimes it is critical to overall success. Flashnet Communication ( a nationwide Internet service provider in the US that has been experiencing rapid growth ( recently determined that performance and future prosperity are linked, and took steps to implement solutions to meet those needs.Top priorities demanded by all of its customers include fast access to email and rapid response from the news server. As system administrator, Chris Bellomy was grappling with these issues and exploring solutions that would satisfy his customers. Bellomy ultimately decided upon Seek Systems and the Xcelerator to boost performance in existing hardware. Flashnet had already deployed two SUN E4000 Enterprise Servers running Solaris as the foundation for its computing system. Performance was nominal and did not become an issue until the quantity of dial-up and mail accounts began to grow rapidly. Bellomy had isolated each of these transaction-intensive applications (mail and news) on separate machines. Even so, I/O performance was not high enough. The news server was bottlenecked by the history file (343Mb and growing), and the mail server was slowed by the password verification scheme of the standard Solaris POP3 mail software (NSCD). Because the Mail server was running about 1000 POP3 connections per second, this was a critical area in which to increase performance. In his tuning process, Bellomy first started isolating processes on different CPUs, then isolating "hot" data on specific storage volumes. The news server was obviously bottlenecked at the history file, but Mail had different problems. New software had been written by Bellomy's group using a Berkeley database application to make the password verification process more efficient. The new code succeeded in creating a more efficient process, but the internal dynamics of CPU cache utilisation changed. The password verification table that was in the CPU cache was now being parsed from a flat file on hard disk and was painfully slow. All I/O was stopped while the password table was written to disk. Several combinations of isolated disk and RAID 0 arrays were tested but none could yield the performance needed. "We needed lightning-fast access," insists Bellomy. The first configuration with a 4Gb disk was running at 100 per cent busy when polled. Bellomy's group ran IOSTAT to analyse traffic and confirmed that conventional storage (single disk or array) was busy at such a high percentage of the time that disks would never keep up with data. It was at this point that Solid State Disk was considered to optimise the bottlenecked processes. The solution Bellomy brought in was a Seek Xcelerator with a 4Gb hard disk and 512Mb of Cache. The Xcelerator with Adaptive SSD was configured with dual host controllers so that there would be no I/O contention in the bus queue priority. Additionally, the Xcelerator was partitioned into two volumes. Flashnet wanted it to appear to operate as two different machines. Adaptive SSD demonstrated its management free performance during the installation phase. Bellomy assigned this project to one of his junior staff members. Seek Service and the Xcelerator worked so well that Bellomy never got involved with the installation details. How did the Xcelerator perform? "Rock solid," claims Bellomy. "We were able to cut CPU load averages by a factor of 7 [from 21 processes down to three]. I was hoping to cut it in half... I was overwhelmed that it was cut to three." What does this mean for the future? Bellomy explains: "We will now be able to scale [our business] to double the current size!" All of this will be accomplished without purchasing new hardware. There is not a more powerful punch than exceeding expectations. The Xcelerator extended the life of existing hardware that now painlessly supports twice the business. Ajith Ram (c) 1998 Seek Systems, Inc.
This was first published in August 1999