IT Pro Verdict
LeftHand Networks shows off everything that's good about iSCSI with a virtual storage solution that includes a quality range of features in the base product, easy management and almost limitless expansion possibilities.
In the circus that is network storage there's a new main attraction taking centre stage. For far too long iSCSI has had to wait in the wings but no longer as small to medium businesses and mid-sized enterprises realise that it's a far more cost-effective alternative to overpriced, overrated and overly complex fibre channel solutions.
Formed in 1999, LeftHand Networks has focused entirely on iSCSI and its latest SAN/iQ 7 Storage Software Platform aims to deliver a range of enterprise level storage features and fault tolerance. The backend system is where all the action is and SAN/iQ scores highly here as, unlike many FC products, it doesn't tie you to proprietary hardware. The software is currently certified with two HP ProLiants and a single IBM System server and LeftHand Networks offers its own NSM 160 appliance. The software is implemented as a customised Linux kernel and installation on your chosen certified platform only takes a few minutes. Another advantage of this modus operandi is you can opt for any disk interface you fancy.
The main concept behind SAN/iQ 7 is clustering over Ethernet which allows you to gather together multiple physical servers and present all their storage as a single pool. Fault tolerance starts at the server level as SAN/iQ can configure and manage certified RAID controllers and defaults to hardware managed RAID-5 on each server.
The storage pool is then carved up into virtual volumes which are automatically striped across all drives and server nodes contained in the cluster. SAN/iQ is priced per node but there are no limits to how many a cluster can contain. FC SAN solutions that require a head unit are restricted as only so many disk arrays can be added. SAN/iQ allows you to keep on adding new nodes to a cluster and the data will be automatically re-striped across them.
Clusters are managed using an MMC snap-in and we found the central administrative console (CMC) easy enough to use. You start by allowing CMC to auto-discover all modules where you can select each one and configure the RAID functions. Next, you add the modules to management groups which define their physical location and allow them to communicate status information to each other. Now you create your clusters and provide them with a virtual IP address. All physical network ports in the cluster are gathered together in a fat trunk with fault tolerance and load balancing and all access to virtual storage is over this one IP address.
A valuable feature of SAN/iQ is the base price includes four key technologies. Synchronous replication, or network RAID, functions at the virtual volume level and is similar to mirroring. However, as data is replicated it is written across the same cluster but skewed so the same blocks don't use the same server. During volume creation you have options for two-way and three-way replication where the former can survive the loss of one physical server and the latter can handle the loss of two.
Next up is thin provisioning which is designed to minimise wasted disk space. You decide how big your virtual volume should be but on creation it only starts as a 128MB physical volume. This grows dynamically in 128MB increments as demand dictates and you can set thresholds to warn when the virtual volume is filling up. If this happens you just increase its size from the CMC.
For access control multiple volumes can be added to a single list, read or read/write access can be set and authentication groups used to determine which initiators are allowed to access the targets. We have one minor complaint here as clusters cannot automatically detect available initiators so you'll have to enter them manually.
The IQN convention is complex enough as it is and as we've already found, typing these in can lead to mistakes.
The third feature included is volume snapshots which can be scheduled regularly or taken on demand. When a snapshot is taken the original volume is frozen, a new layer is created and all further write operations are directed to this. All snapshots are combined into the virtual volume and any read requests are directed to the snapshot that contains the relevant data. Data recovery is a cinch as you merely select the snapshot you want to rollback to. Furthermore, any snapshot can be mounted as a separate virtual volume for file recovery or to be used by a backup server.
Last but certainly not least of the base features comes asynchronous replication. This is configured on a per volume basis so you can decide which data should be sent offsite and it includes bandwidth management and throttling to control WAN utilisation of remote copies. Another bonus over FC SANs pops up here as SAN/IQ doesn't require identical or similar physical servers at each location so you can use low cost systems at the remote site.
Other options are available as LeftHand offers a multi-server high availability disaster recovery pack which supports clusters containing geographically distributed physical nodes. These will require Gigabit Ethernet links to function but do avoid any wastage incurred by having standby arrays waiting for failover. A Microsoft feature pack is also available which brings MPIO into the picture and utilises the Windows volume shadow service.
Typical markets for iSCSI storage applications are SMBs and mid-range enterprises - the types of business that don't have deep pockets or aren't already locked in to expensive FC SANs. The list of supported platforms really needs to be expanded but we found SAN/IQ easy to install, deploy and manage and were impressed with its extreme expansion capabilities. The starting price may initially seen high but bear in mind that this includes a range of features many competing vendors will charge extra for. Another bonus is SAN/iQ supports VMware's ESX Server allowing clusters to be built from virtual machines. In fact, this is proving so popular that LeftHand advised us that VMware storage virtualisation now accounts for around half its sales.
Verdict
LeftHand Networks shows off everything that's good about iSCSI with a virtual storage solution that includes a quality range of features in the base product, easy management and almost limitless expansion possibilities.
Certified for the following servers: HP ProLiant DL380 G4; HP ProLiant DL320s; IBM System x3650. Processor: Minimum - DL380 - 2.8GHz; DL320s - 2.4GHz, x3650 - 3GHz Memory: Minimum 2GB of RAM Disk drives: Supports SCSI, SATA, SAS Storage controllers: DL380 - SmartArray; 6i, DL320s - SmartArray P400; x3650 - ServeRAID 8k
