In our previous post, we talked about what LaserVault ViTL with iSCSI connectivity is and why we think it is an important addition for IBM i environments. This time, we wanted to get a little more technical and talk about what we’re seeing in our performance testing.
When we started looking at iSCSI connectivity for ViTL, one of the obvious questions was: How fast can we actually make it?
The short answer: pretty fast.
And perhaps more importantly, iSCSI gives IBM i customers another way to connect to ViTL without requiring specialized Fibre Channel hardware.
So, What Kind of Network Do You Need?
If you’re deploying ViTL over iSCSI, we’d recommend 10 Gigabit Ethernet if you want good performance.
You can run it over 1 Gigabit Ethernet, but you’re going to run into the limits of the network pretty quickly. A 1 GbE connection tops out at roughly 120 MB/s under ideal conditions.
With 10 GbE, however, things get considerably more interesting.
In our current testing environment, a single 10 Gigabit Ethernet connection produced roughly 380–400 MB/s of throughput.
That’s a respectable amount of data moving through an Ethernet connection.
And we’re not necessarily done squeezing performance out of it, either. There is still more testing we’d like to do to see how far we can push it.
What About Multiple Tape Drives?
Here’s where things get even more interesting.
We also tested two tape drives performing save operations in parallel. Instead of seeing the same roughly 400 MB/s ceiling, we were able to push aggregate throughput to around 600 MB/s. As with any performance testing, actual results will vary depending on the network, server, storage, IBM i workload, and other components in the environment.
Each tape drive was doing roughly 300 MB/s.
That’s important because real-world backup environments aren’t always about one giant stream of data. Being able to run multiple operations in parallel gives you another way to take advantage of the available network bandwidth.
That can be useful in IBM i environments where multiple save operations are running at the same time or where backup windows are already taking advantage of multiple tape devices.
What About Network Redundancy?
There isn’t a complicated special network configuration required for ViTL iSCSI.
The usual networking best practices still apply, though.
For example, you can use NIC teaming or bonding to provide redundancy. If one network interface fails, the other can continue carrying traffic. Depending on the configuration, teaming can also provide additional aggregate throughput.
In other words, you can build your network the way you’d normally build a reliable server network rather than having to invent some special architecture just for ViTL.
What About the Cloud?
This is one of the areas we’re particularly interested in.
We did some initial testing with ViTL in IBM Cloud and saw roughly 150–180 MB/s of throughput.
There is an important caveat here: the test environment was using a relatively low-tier virtual machine with a 2 Gigabit network limitation. In cloud environments, the VM instance you choose can have a major impact on the amount of network bandwidth available.
So that result shouldn’t be interpreted as a hard limit for ViTL in IBM Cloud.
There’s still plenty more testing to do with higher-performance virtual machines and different configurations.
And we’d also like to see how ViTL behaves in other cloud environments.
Can You Use Fibre Channel and iSCSI Together?
Yep.
You don’t necessarily have to pick one or the other.
ViTL can support Fibre Channel and iSCSI within the same installation, which gives you some useful flexibility.
For example, you might have an on-premises IBM i system where Fibre Channel makes the most sense because you want maximum local performance.
At the same time, you could have another IBM i environment that needs to access that same virtual tape library over the network using iSCSI.
That’s particularly interesting when you start thinking about hybrid environments.
Fibre Channel and iSCSI are essentially giving you different transport options for getting to the same virtual tape infrastructure.
What About Existing ViTL Fibre Channel Customers?
You don’t need to convert your existing virtual tapes just because you’re adding iSCSI connectivity.
ViTL continues to present itself to IBM i as a tape library and tape drive. From the IBM i side, the backup software still interacts with it like a tape device.
That means you can continue using the backup tools and workflows you’re already familiar with, including BRMS, Robot Save, and native IBM i save and restore commands.
The underlying connectivity can change without requiring you to completely rethink your backup process. That means you can use the connectivity that makes the most sense for each IBM i environment without having to maintain completely separate virtual tape solutions.
So, Where Does That Leave Us?
We’re still testing and learning, but the results so far are encouraging. iSCSI gives ViTL another way to connect to IBM i, and the performance we’re seeing over Ethernet makes it a practical option for a range of environments.
What’s especially interesting is the flexibility. You can use iSCSI for a new ViTL deployment, add it alongside Fibre Channel, or use it as part of a cloud or hybrid IBM i environment. And from the IBM i side, the virtual tape experience remains the same.
There’s still more testing to do, particularly around different network configurations and cloud environments. But so far, we’re seeing iSCSI do what we hoped it would: provide a straightforward way to connect IBM i to ViTL using the network infrastructure many organizations already have.
New to ViTL with iSCSI? Read our previous post, [LaserVault ViTL with iSCSI: Another Option for IBM i Virtual Tape], for an overview of what iSCSI connectivity is, how it works with ViTL, and why it matters for IBM i shops.
About LaserVault
For over 35 years, LaserVault (Electronic Storage Corporation) has been building reliable software solutions for IBM Power Systems. Our team combines deep technical experience with responsive support to help businesses and resellers get exactly what they need—fast.
We also partner with IBM, Cohesity, Rubrik, ExaGrid, Everpure and other technical experts to deliver trusted, modern solutions.
Visit laservault.com or email info@laservault.com to request a quote, schedule a demo, or ask about our reseller program.
