LeftHand Networks

What happens if your e-mail servers go down? Do you have a back-up plan in place? This week, the Reviewmeister checks out two products that provide backup for Exchange e-mail servers.

Let’s start with LeftHand Networks, which provided the full-meal deal in the form of a storage-area network running its SAN/iQ Remote IP Copy application. Because LeftHand completes 100% of its clients’ installations, we let its engineers install the SAN and software in our lab. The SAN and software combination – called the Network Storage Module (NSM) – is mirrored from site to site.

The SAN comprised two rackable RAID frames with eight drives in each. The drives were configured in what LeftHand calls a RAID 10 configuration (actually RAID 5/2 combination) along with its software. Installation of the hardware took about an hour with two people; initial software installation took half that.

We set up two stores at each ‘site’ for each Exchange server running at that site on one NSM.

NSMs swap snapshots of data from a source to a target. If the data link speed between NSMs supports it, frequent snapshots can be taken and sent from source to target. Because there are fluctuations in mail server transactions, frequent snapshots need to be taken to ensure transactions aren’t lost. The product can be tuned so that frequent snapshots are taken.

We initially connected to the LeftHand Networks SAN with a notebook and null-modem serial cable. The devices are mirrored together over IP – outside of the connection(s) to the Exchange Servers. The required IP connectivity doesn’t like network address translation, and therefore requires a virtual LAN or VPN connection between sites. We used a Point-to-Point Tunneling Protocol VPN connection.

The NMS is configured for four parameters: size and type of Windows NT File System volume, output bandwidth to use (bandwidth can be throttled to optimize links), snapshot information and scheduling.

The management tools provided with this product were useful, but not necessarily intuitive. Replacing a failed drive stymied us until we read through the help screens because we couldn’t understand the procedure from the documentation.

The Exchange-specific recommendation we followed asked that once a failover had occurred, that you make your way through 27 steps to bring Exchange back online at the hotsite/back-up site. We did this, twice, and the steps worked.

The most onerous of these steps was to bring Exchange online at the recovery site in Recovery mode, which added more than an hour to the point where we could bring either version of Exchange back online.

Documentation comes in three sets, one for Remote IP copy, one for SAN/iQ and one for the SAN200 installation. They’re good and descriptive documents, although the Exchange-specific information came via a PDF rather than through the documents. The Exchange instructions were good enough.

The fact that the LeftHand Networks NSMs can replicate a number of platform stores – including Linux, Windows 2000, Windows 2003 and numerous file systems – is to its benefit, but in terms of high availability specifically for Exchange, it lagged the competition.

Coming in at the high end of the pricing chart, LeftHand Networks provides a holistic solution – all of the storage components are included for organizations that find themselves facing mushrooming storage problems – and in need of all of the bits to make the solution work.

For the full report, go to https://www.nwfusion.com/reviews/2004/0503rev.html