iQstor iQ2850
The virtualization of systems through a Virtual Operating Environment (VOE), now garners the lion's share of attention of CIOs. It is impossible to maximize the benefits of a VOE, such as VMware Virtual Infrastructure, however, without first implementing SAN-based storage. Especially at SMB sites, too often there is no SAN for harnessing system and storage virtualization synergies. By leveraging existing Ethernet infrastructure and not burdening IT administrators with new infrastructure to manage, IT can immediately realize all the benefits of a SAN with iQstor's iQ2850.
Further simplifying SAN implementation, the VMware ESX file system (VMFS) handles logical disks belonging to VMs in a way that is analogous to CD-ROM image files. In this way, VMFS encapsulates a VM's files within a logical disk and eliminates the burden of ensuring exclusive ownership of logical disks in order to protect the integrity of the VM's file system. More importantly, advanced VI features, such as VMotion, are designed specifically to leverage shared storage to provide a virtual machine (VM) with mobility for load balancing and disaster recovery. That explains why strong growth in server virtualization is spurring strong iSCSI adoption as the least complicated way to migrate from DAS to a SAN.
To maximize the value proposition of the iQ2850, iQstor utilizes enterprise-class Seagate Barracuda® ES.2 SATA drives. What distinguishes this line of drives is the availability of SAS or SATA interface electronics for drives with all other opponents identical. With the same recording platters and the same firmware to reduce rotational vibration, the reliability of Barracuda ES.2 SATA and SAS drives are the same.
What's more, the iQ2850 sports fully redundant, hot-swappable components. In particular, iQstor puts a Fibre Channel interface on each of the SATA drives and connects them to one of two iSCSI controllers via one of two 4Gbps FC arbitrated loops, which allows the controllers to address up to 240 drives. As a result, iQ2850 can support significant site storage expansion without addition of JBOD expansion units, which for archival applications, such as D2D backup, is a highly cost-effective way to meet site I/O traffic patterns and requirements.
Given the quality of the drives and the system's FC arbitrated loop architecture, we were not surprised to see our sequential I/O benchmarks on VMs reduced to a race to reach wire-speed-about 112MB per second-for iSCSI connections. With one active I/O process on one VM, I/O throughput for sequential reads using a VDisk from our RAID 1+0 storage pool was pegged at 80MB per second. That throughput rate was nearly twice that of a VDisk from our RAID 5 pool, which was measured at 45MB per second. With battery-backed cache in the controllers and local UPS devices for systems, testing with a typical write-back caching configuration put write performance on a par with read performance for VDisks from both pools.
More importantly, that sequential I/O performance was for a single process on a single VM. With two I/O processes utilizing two distinct drives, throughput for standard 8KB reads rose to 105MB per second and for large-block (64KB) reads rose to 160MB using our RAID 1+0 storage pool. At that point, however, the structure of the RAID arrays in the storage pool becomes subsidiary to the EXS server's ability to leverage the eight iSCSI connections provided by the iQ2850. With the iQ2850 iSCSI storage system, I/O scalability is much more likely to be a sever scalability issue rather than a storage system issue.
