SAN FRANCISCO (10/24/2003) – Just as Ethernet networking devices have evolved from straightforward hubs to layer 2 switches to layer 7 application-aware switches, so are SAN switches evolving. The Maxxan Systems Inc. Maxxan MXV320 Intelligent Application Switch corresponds to a layer 7 Ethernet switch, providing application-layer functions including virtualization of storage, storage gateway capability, replication and mirroring, and snapshot-based backups.
The replication functions are especially noteworthy. They make it possible to create mirrored or replicated storage or snapshot backups in a vendor-neutral manner, using any backup or storage management software desired, even with a multivendor SAN. This is a tremendous benefit in large organizations with multivendor SANs. It is, as far as I know, a totally unique offering.
The Virtual Route
The MXV320 is a chassis-based FC (Fibre Channel) switch that can support up to 320 1Gbps FC ports or 160 2Gbps FC ports. It also supports two intelligent storage blades, the SG210m and SA200f. The SG210m is a Windows Storage Server-based gateway that can make any FC storage attached through the SG210m switch available as Windows file-server storage. The SA200f provides both Windows and NFS (Network File System) NAS functionality, plus easily accessible storage replication, mirroring, and virtualization.
The blade has a Web-based management application that monitors fan speeds, temperatures, and power supplies, plus a serial console for initial configuration. The SANCruiser application manages the switch hardware, most hardware management for the blade, and provides a topological view of the entire SAN and its management functions. Finally, the SA200f runs a Linux kernel and the IPStor application for storage virtualization, NAS, mirroring, replication, and backup functions.
Storage virtualization adds a layer of abstraction between actual storage devices and host computers. This means that the volume seen by a host can actually be made up of blocks from multiple devices, either local or remote. The SA200f switch ports can act as either target or initiator ports, so they can act as storage devices to a host and as a host to the storage devices. However, the ports must be set manually to target mode or left in the default initiator mode — they don’t switch automatically.
IPStor’s nice wizard setup makes it simple to control virtual storage. The Add Storage wizard can virtualize, service-enable, unassign or import storage, while the Virtualize wizard enables virtualization, reformatting a disk or disks to add a virtualization header. The Service-enable wizard uses the virtual header on another disk to create a virtual virtual disk so existing data isn’t lost. The Import wizard reads header info from volumes that have already been virtualized on another switch, which comes in handy when moving existing resources to a new switch.
Management capabilities are excellent for the virtual SAN functions, though administrators will still need to use separate vendor-supplied applications to administer the various devices in the SAN. Virtual disks can be created from multiple devices from multiple vendors, enabling a truly flexible SAN environment. Once virtual disks are created, you can set up replication and mirroring. Replication can happen when a set threshold of data has been changed, at set times, or at given intervals. The application will scan for differences so a full replication isn’t necessary over a WAN link — a mirror can be created, shipped to a remote site, and replication will handle the differences.
NAS resources can also be easily created using a Windows or NFS. The Windows version of the NAS reads AD (Active Directory) or NT domain information so the software can easily be integrated into an existing Windows network. Share modes include Samba, an NT domain mode, a domain controller mode, a server mode, or a single server mode, with or without AD. Storage can be added to organization units within AD, which means that the NAS functions can integrate easily into almost any network.
Benefits of the Blade
The SA200f blade has two 10/100/1000 Ethernet ports, which can use 802.3ad or IP-based trunking to provide one 2Gbps Ethernet connection. The blade also includes a 10/100 Ethernet management port and 10 1Gbps or 2Gbps FC ports, plus dual 2.4GHz Xeon processors, and 2GB of RAM standard, with up to 12GB supported. The SA200f provides the virtualization functions and is surprisingly mature for a first-generation product.
The SANCruiser application, meanwhile, offers an interesting topographical mapping function that does a good job of coherently representing a complex SAN topology. The interface includes switch-hardware management tools, such as real-time status of all ports, the SA200f blade hardware, and the SAN itself. SANCruiser can also notify administrators by e-mail if thresholds are crossed or problems occur.
To create volumes, administrators have an easy-to-use SAN resource wizard that can create LUNs (Logical Unit Numbers) as SAN resources, assign them to hosts, expand LUN sizes, and do backups via a raw device. Maxxan includes separate read and write cache capabilities, so a separate LUN can be designated as a SafeCache write cache, or a HotZone read cache. These caches improve replication performance over WAN links and allow for asynchronous mirroring.
Enabling snapshots for image backups requires a separate SAN virtual device to store the snapshots. Snapshot functionality includes a time mark, a very interesting feature that creates incremental snapshots so there’s no need to restore an entire block device to get one file back.
The switch has a number of notable FC features, too. One is automatic promotion, used in the creation of zones, similar to Ethernet VLANs. If a switch port is added to a zone, the device attached to the port is also added so a device isn’t accidentally added (or not added) to a zone. Another feature is rolling firmware upgrades, allowing upgrades to be done without downing the switch or losing storage device access.
The Maxxan MXV320 Intelligent Application Switch, in combination with the SA200f blade, provides virtualization that is potentially very useful, especially in multivendor SAN environments. The average price of US$100,000 is fair, considering the switch’s functionality and its extra virtualization and gateway features. Because the switch can make a remote storage device appear to be a locally attached raw FC device, distance and manufacturer become irrelevant — just what’s needed to deal with the real world of multivendor devices.
