iSCSI bandwidth

[gshaw]

Another quick pop quiz to see what's working in your environments... how many 1Gb connections are you running on your iSCSI SANs to get good performance?

 

The P2000 SAN we're looking at looks to have 4 ports per controller on the G3 model which should be plenty, the documents seem to suggest 1Gb connection to each switch (2 switches for multipathing)

 

Is that enough to give performance for servers virtualisation or can you use the 2 extra ports as well? I've read that link aggregation isn't recommended on iSCSI, MPIO is the right way but not seen much about using more than 1 x Gb link from SAN to switch?

 

Granted "enough performance" is one of those "how long is a piece of string" questions but for the kind of installs people are running here you probably can see the kind of environment we're all looking at

[sacrej]

we have a dell md 3200i which has two controllers (8ports) these all go into a switch and then each server has 4 ports to this switch

we have about 10 vm's running on SCVMM/Hyper-v and to be honest, bandwidth is NOT an issue. we are running 12 15k sas drives

just make sure your adapters and switch are setup correctly (jumbo frames etc)

we use MPIO, because....well....aggregation isnt an option (the san doesnt allow it)

 

oh and we will be getting a second switch for multipathing at some point....just err...havent gotten around to it

[mrbios]

4 x 2TB drives split into 2 logical drives 2 LUNs in RAID6 going over 1 iSCSI connection - 1200 users using it daily as well as an exchange server mailboxes being stored via the same single connection. Performance? perfectly fine, most networks have complete overkill setups, you simply don't need huge £10k+ solutions unless you have a damn good reason.

 

If we were running our VMs off it each Host would have it's own iSCSI connection and it's own RAID6 array with up to 7 VMs per host.

 

The 2 Logical drives are used for storing all network files, home folders, programs and exchange mailboxes.

Edited March 2, 2011 by mrbios

[jamesfed]

I think it has always been more about IOPs on your drives than bandwith on your network when it comes to running VMs off a SAN (assuming thats what you are looking at).

[gshaw]

Yup, just making sure I've covered everything before committing to a solution. The P2000 G3 SAN we're looking at has 4 ports per controller although whether we need to use all of them is debatable. We're looking at 15k SAS disks for the VMs, Exchange and SQL so that should cover the IOPS nicely

 

SATA drives will then give the capacity for file shares etc.

[Butuz]

Single 1Gb link to each san here for VM storage and come no where near saturating a single link so far.

 

Butuz