IBM TotalStorage DS4100

IBM's relationship with Ingenio over the past decade has produced some desirable mid-range storage solutions. As the appliance formerly known as FAStT100, the TotalStorage DS4100 on review is a particularly good example. It offers a modular approach aimed at providing SMEs on a tight budget with an entry-level storage server that can be easily expanded.

The DS4100 concentrates purely on fault-tolerant Fibre Channel SAN applications. Raw storage capacity is impressive, as this well-built 3U chassis has room for 14 Serial ATA hard disks, so with 250GB drives it can go up to 3.5TB. Expansion potential looks just as good, as the review unit is equipped with dual controllers allowing up to seven DS4000 EXP100 enclosures to be added, which can take maximum capacity up to a very healthy 28TB. General fault tolerance is good, with redundant power supplies and fan modules, plus dual RAID controllers and FC (Fibre Channel) ports. The latter are used for host or switch connections, and a third provides a 2Gb/sec FC connection for attaching additional expansion units. All three ports require an appropriate SFP (small form-factor pluggable) module installed. Remote management access is facilitated by a Fast Ethernet port, and local CLI access is available via the serial port.

The bundled Storage Manager Client (SMC) software makes light work of installation, as it automatically searches the network for IBM storage arrays and displays them ready for configuration. There are plenty of wizards, so you can dive straight into array creation by selecting the drives to be included, the array type and LUN assignment. Multiple arrays are supported, so it's possible to mix and match as required, and each is assigned a preferred controller. The DS4100 copes well with extra demand, as you can add new drives to an array when required and use the online capacity expansion feature to increase the size of logical volumes.

Unlike many appliances at this level, the IBM doesn't tie you down to the RAID arrays you initially chose during installation. A dynamic RAID expansion feature allows you to select an existing array and change it on the fly. You can pick any supported array type to change and, although performance will be hit during the rebuild, the data remains available throughout the entire process. If general performance isn't what it should be, you can play with the array's segment size dynamically as well. The SMC makes it easy to modify existing arrays or volumes. You pick the target, make your modifications and leave it to get on with it. If there are problems on the array, a troubleshooter fires up to help remedy it.

During testing, we found general performance to be very good. With a single direct-attached Windows Server 2003 system, we saw the open-source Iometer report a raw read throughput of 189MB/sec. With a second server attached to the same controller and also using the same volume, we saw a cumulative throughput of 376MB/sec. This showed the DS4100 was still able to deliver near wire-speed performance even with two servers sharing the same resources.

Smaller businesses looking for low-cost storage consolidation will find the DS4100 a worthy candidate. It offers an impressive range of fault-tolerant features, plus quality remote management tools. It also allows arrays, volumes and raw capacity to be increased easily as demand dictates.

Author: Dave Mitchell