Questions from an iSCSI noob

[BradI100]

Hi,

In a recent disaster recovery incident I put in place new iscsi storage.  It is not installed per vmware's best practices, because I have it connected to a network 1gb switch.  Though everything is up and running and esxtop is showing good disk latency.

What I am wondering is:

1. What is the harm of having iscsi traffic on the same subnet / vswitch as regular network traffic?  Isn't traffic on the switch traffic?

2.  If it's crucial that I move this to a new subnet, is there a procedure that would let me do it without shutting off the servers and storage?  The storage is a Drobo Elite with 2 iSCSI connections.  They are both connected to the network for redundance.

thanks

[athlon_crazy]

1 - Perhaps this url may help you to understand all the risks. On security perspective, combining iscsi and regular network traffic is not recommended.

2 - Once you change your network for iscsi target, I don't think you can avoid a downtime. Unless you have multiple target lest say target 1 & 2, move all VMs from target 1 to target 2 (via storage vMotion), change network/subnet for target 1 & add to ESX/i this new target, move back VMs to target 1 and do the same for the target 2.

[BradI100]

Thanks, that was a good article.  Still, I am a bit confused about if I create a vlan on a switch and put the storage into it on a different subnet, how does that prevent it from competing with other traffic on the same switch (different vlan)?

Also, for the move to vlan.  Was thinking there might be a way to use the redundant iscsi connections to let me move one connection over at a time.  Probably not, but I can dream!

[athlon_crazy · Accepted solution]

Regardless how many VLAN, it's still logically instead physically separate and a single interconnection may suffer from network bottleneck. If you have an extra budget, get dedicated pSwitch for your iSCSI. My past experienced telling me that, a dedicated switch for iscsi can give you a very good performance.

[BradI100]

Thanks again.  Hey, is there a small switch you like to use for iSCSI?

This is a 50 person organization.  I was considering ordering the  Cisco SLM2008

Your thoughts?

[AndreTheGiant]

Check for a giga-switch that support Jumbo Frames.

I use Dell PowerConnect 5424 switches, but also other could be fine.

Andre

[athlon_crazy]

Cheapest can do VLAN and support jumbo frames, HP Procurve 1800 series