Xsan and Stornext – A brief review of differences

Stornext is a shared storage environment that offers high speeds and large sizes that scale independently.

Apple licensed StorNext from Quantum and re-branded it as Xsan. So its very common to hear that “Xsan is StorNext.” But StorNext is not Xsan.

I came from Xsan into StorNext and it gave me a great advantage to understanding how things work. But Apple watered down the capabilities of SN to create a more user friendly version. What this really means is that if you have an Xsan system, running on Mac metadata controllers, you will have fewer features available (and often times this is perfectly fine). But if your system runs on Stornext MDCs such as windows or linux servers (or more recently the Quantum Stornext appliances) then many extra features are available.

Control Interface

In Xsan, your entire SAN is managed through an OS X app called Xsan Admin. In recent OSes the functionality has recently been folded into the Server app.This is where you create volumes, create metadata controllers, assign failover, import clients, etc. Everything is controlled through that interface (As a side note, that interface sucks). The information updated there can be shoddy and it doesn’t always successfully execute commands. Xsan admins can end up spending much of their time in the CLI.

In StorNext, it is a web interface hosted on the active controller. This web interface reeks of 1998 html but provides a decent bit of functionality. I’ll set that although you can do most tasks through this interface, many tasks are just easier to do in the shell.

The two are very similar in command line. Most of the binaries are exactly the same. Some have specific functionality removed in Xsan. But anyone familiar with one should feel pretty comfortable in the other.

Storage Manager

Storage manager is the component in Stornext that is responsible for tiered storage. This adds the ability for stornext to integrate with a tape library for archiving, or to tier data to storage with different speeds. Storage manager handles the “automatic” movement between the tiers.

Storage manager is an option that is not available for pure Xsan environments. Apple removed this option to keep the Xsan offerings as simple as possible. Xsan clients in a stornext environment are able to interact with systems that are storage manager enabled.

High Availability

If you have a regular Stornext Volume with 2 MDCs, High availability and failover operate the same way as Xsan, with the standby controller taking over the processes when the active controller is no longer available.

HA is done slightly differently in SN if you have a managed volume. Because of the various extra components required with Storage Manager, an additional volume is created called hafs. This volume is mounted by both MDCs and used for (among many other things) keeping track of which controller is active.

Replication

Another feature not included in Xsan is the Stornext replication. Moving data between two volumes, or between SANs across the LAN or WAN, this is a great feature for onsite or offsite backup of SAN data.

Deduplication

Working in conjunction with replication, the replicated data can be de-duped on the destination.

Clients

The Xsan client is built-in to OS X along with all the required licensing. So adding more clients is as simple as connecting and mounting. Windows and Linux clients, however, require a client license for each one. The client licenses generally run a little less than $2k each. Once purchased, You have to send Qauntum some info from your MDCs which they use to generate a new license file. This whole process can take a couple of days sometimes, so you’d better not be in a hurry.
All licensing for the entire SAN is stored in the single license file. So whether its 100 or just 1 new license that you’re buying, you still have to wait and replace your current license file.
Interoperability is fully supported with these too. Mac clients can easily mount a Stornext system. No extra licensing needed. But to add a windows or linux client to an Xsan installation you need to do the same licensing dance (the Xsan controllers recognize the license file the same way).

Upgrading from Xsan to StorNext

Upgrading can be as simple as moving the config file to a set of Stornext MDCs and making sure they can see the LUNs.
There are some caveats if you some weird custom configs, and you should backup the config file just in case. But for the most part, all the configuration parameters in Xsan are supported in Stornext.

Leave a Reply

Your email address will not be published. Required fields are marked *

* Copy This Password *

* Type Or Paste Password Here *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>