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Home >> Success Stories >> Mission Critical Linux Success Stories
FlashDisk Aids in Testing of Linux Clustering Software The Organization - www.missioncriticallinux.com What's the world fastest growing open source code operating system? Linux, of course! It has rapidly moved up the food chain from dynamic dot.coms using custom-built servers, into enterprise-level IT shops using best-of-breed Linux servers and open systems storage. Founded in mid-1999, Mission Critical Linux provides the sophisticated technical support services and clustering software required by all types of organizations serious about Linux. In fact, Silicon Graphics (SGI) and Mission Critical Linux recently signed an agreement to deliver support services to SGI's customers around the world. This Lowell, Massachusetts-based company's patented Web-based, Secure Service Technology enables an organization to link its servers to the support team at Mission Critical Linux. To this end, an organization gains a virtual support team capable of monitoring, detecting, and correcting problems on any type of Linux server - Web, Oracle, or Intranet. Mission Critical Linux is one of the first companies to develop enterprise-level clustering products for Linux. The Convolo Cluster software enables two, high-volume servers to share the same storage system, and to provide failover if one server fails and leaves the cluster. Despite its focus on the enterprise, Mission Critical Linux also embraces the Linux community's tradition of sharing tools to enhance this OS. As a result, Kimberlite Cluster, which provides the core technology for Convolo Cluster, enables any Linux user to put together a two-server cluster with failover capability.
FlashDisk Customer Profile as Told By Mission Critical Linux "We identified that Linux lacked the capability to handle enterprise-level clustering with failover. In other words, if one server in the cluster goes down, the other server can jump in instantaneously and take over. Since members of our cluster team had developed Digital Equipment Corp.'s True 64 cluster technology, they knew how to write the Linux code for Convolo Cluster. Convolo Cluster, which supports a two-server cluster, is designed around the one single failure point in a cluster- the RAID storage array. Because multiple devices need access to storage at the same time, we had to develop and to test Convolo Cluster using a fault-tolerant RAID storage system. We also needed a storage system that could connect to multiple servers so they could easily access the same storage device and share data. Performance was another factor. Each server needed to access data at top speed without either server experiencing any performance degradation. We compiled a list of several RAID storage vendors, including Winchester Systems of Burlington, Massachusetts. Since we wanted to test our clustering software with different storage systems, we asked each vendor for an evaluation unit for several months. The technical staff at Winchester Systems immediately understood the potential benefit of our Convolo Cluster. In no time we had a Winchester Systems' FlashDisk RAID storage system running in our test laboratory. The FlashDisk evaluation system had everything we were looking for-all dual-redundant, hot swappable components, including all controller logic and power supplies. The FlashDisk's controller cache offers another level of sophistication. The mirrored cache between the controllers allows the second controller to take over if the primary one fails or if the there is a cache failure. To this end, the FlashDisk can ensure that data won't be lost and service won't be interrupted. Linux users don't want to compromise speed, stability, or price. Since Fibre Channel is still expensive for a lot of Linux users, we decided to stick with a SCSI-based storage system for the initial release of our Convolo Cluster. Besides SCSI technology, which is rock solid, continues to increase in data rate performance with each new SCSI version. We chose Winchester Systems' FlashDisk for another reason, too. Its SCSI bus can connect to any open systems SCSI server, such as a Linux server or a Windows NT server. Unlike some of the other vendors, Winchester Systems equips all of its FlashDisk models with dual-host channels. This feature greatly simplified setting up the cluster. Without dual-host channels, we would've had to put two hosts on the same SCSI bus. That could've presented problems. If you try to add another host to the SCSI bus and that bus already has a fully operational host, the host-based controller could issue a SCSI bus reset. This reset, in turn, could have an impact on all of the drives, as well as the controller at the other end. Data corruption may or may not occur. Nevertheless, you don't want to take that chance. In contrast, each dual-host channel takes care of getting data from each channel onto the RAID array. To test our Convolo Cluster, we used a variety of RAID levels. For example, for an NFS cluster, we used level 5. With an Oracle database cluster, we used either level 0+1 or level 1+0. We easily did all the RAID level configurations by going through the FlashDisk's front panel or by connecting to the console serial port of the array. Our cluster developers, as well as myself, appreciated how easily the FlashDisk could be configured. Our tests included connecting some high-performance Linux servers to the FlashDisk. The server vendors included VA Linux, Penguin Computing, and Network Engine. The benchmarks used included Bonnie++, I/O Storm, I/O Bench, and DiskStone. Overall, we got better-than-expected performance from the FlashDisk. For example, with two hosts writing large block transfers, we got a speed of 16 MB or 17 MB per second from each host. The FlashDisk performed better than the RAID systems we've used in the past. As a result of our experience with the FlashDisk, we bought a small FlashDisk for the cluster group's research and development tasks, and a larger FlashDisk for our in-house NFS cluster. Our in-house system has undergone a major upgrade from a Dell PowerEdge Quad-CPU server with a Dell PowerVault RAID system to a VA Linux with a dual CPU and a Winchester Systems' FlashDisk. The performance improvement has all but blown us away. Our developers also have noticed a remarkable increase in system responsiveness since the migration. Our relationship with Winchester Systems continues to grow. At LinuxWorld 2000 and Oracle OpenWorld 2000, we demonstrated our commercial Convolo Cluster software, using a FlashDisk as the RAID storage system. At Intel Developers Forum, we ran Convolo Cluster on the new Intel Itanium (IA-64) server attached to a FlashDisk. FlashDisk is scheduled to be in our booth at other upcoming Linux shows as well."
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