The other day I was working for a couple of hours with a colleague on trying to figure out why, regardless of what we did in terms of multipath configuration (bonded IP network+multiple virtual openiscsi initiator ports per bond + dm-multipath or multiple NICs on the same subnet + one openiscsi initiator per physical nic + dm-multipath), we were unable to get more than between 110 & 125MB/sec of throughput from our RHEL 5.4 host to our EqualLogic iSCSI SAN volumes.The expectation was to see more than 200MB/sec throughput but of course, we were essentially seeing about 1 paths’ worth of throughput. Continue reading →
Linux: Configure “bridge at boot” for NIC(s) in Fedora 13
Sometimes, for instance when having a limited number of Network Interface Cards (NICs) on a system that will be used for a Linux hosted platform virtualization solution (and you’re running Fedora 13), the easiest approach to giving each of the guests “direct” access to a network is to configure the physical devices as bridges on the host.
This will permit the libvirt virtualization (management) abstraction interface to easily build “briges of bridges” that in turn let a Kernel Virtual Machine (KVM) guest get it’s own “public” (only in quotes because I happen to think the average bear would not be so silly as to put their Linux/KVM host directly onto the internet. Right???) IP address and route its traffic directly onto the ether (via the lower levels of the IP stack of the host environment).
There are, as is the case with all things Linux or UNIX, a couple of ways to skin this particular bear (sorry, that’s bad!), but the one that makes the most sense to me is to have init take care of the configuration as part of the system boot process (when the network service executes). And doing that, although in its simplest form requires access to a terminal window and a text editor on the Fedora host, is actually very simple, once you know what you’re doing. Hopefully, the following will help you learn (if you don’t already know and are only reading this because you’re looking around and are a very bored individual). Continue reading →
Linux: Using multipath to improve performance for your iSCSI array
As part of my self-learning activities at work, I’m playing with a multi-homed EM64T based server, Linux (Fedora 13), the iscsi-initiator-utils and an EqualLogic PS series RAID array. In the previous installment, I gave an overview on how to make the Volume(s)/LUN(s) exported from the array appear on and be usable from the Linux host. In this installment I’ll discuss how to configure the dm-multipath sub-system to aggregate multiple network paths for availability and load-balancing purposes.
But before we get into the nitty-gritty of that, I just wanted to touch on a problem I’ve been having in setting up multipath over IPv4 on my Fedora 13 host. Now, keep in mind that the Fedora host I’m using has been “tweaked” and “messed with” (a lot), so it ain’t no “fresh install” here… That said, I’ve been having problems getting both of my array-facing NICs to successfully ping the EqualLogic Group IP address.
So, if you’re able to ping the EqualLogic array’s group IP address from both Ethernet NICs, setting up the iSCSI initiator as well as the DM multipath module(s) is very much a “straight forward” exercise. Continue reading →
Fedora 13: Multi-NIC and IP traffic problems
Are you only seeing IP traffic on one of two (or more) interfaces in a Fedora 13 environment? I was, and here I’ll try to explain how I went about resolving (at least working around) the problem for my multi-homed dedicated iSCSI network.
So, as part of playing in my lab environment to configure Fedora 13 and an iSCSI RAID array (EqualLogic PS Series array) for multipathing, I ran into a bit of a snag: Continue reading →
EqualLogic storage (iSCSI) on Fedora 13
I’ve started playing with iSCSI devices in earnest. Specifically, I’m having a lot of fun playing around with an EqualLogic array (PS Series array) at work and getting a Linux (Fedora 13) environment up and running.
It’s pretty straight forward, really.
At its simplest and highest(ish) level: Continue reading →
