ddockter
Contributor
Contributor

iSCSI traffic - VLAN vs dedicated switch

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I have a fairly small vSphere environment - 2 ESX hosts with 6 VM's (will grow to 12+ VM's by the end of the year). My iSCSI SAN only has 1 interface for iSCSI traffic. I currently have a VLAN defined on my GB network traffic switch for the iSCSI traffic. I know the ideal is to have the iSCSI traffic on it's own switch. Would this be overkill for my environment? I can purchase an HP ProCurve 1810 switch for less than $400.

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PaulSvirin
Expert
Expert

Vote for dedication too.

Additionally you can tweak iSCSI performance by overriding "auto-negotiation" and manually

adjusting speed settings on the NIC and switch. This lets you

enable traffic flow control on the NIC and switch, setting Ethernet

jumbo frames on the NIC and switch to 9000 bytes or higher --

transferring far more data in each packet while requiring less

overhead. Jumbo frames are reported to improve throughput as much

as 50%.

---

iSCSI SAN software

--- iSCSI SAN software http://www.starwindsoftware.com

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DSTAVERT
Immortal
Immortal

It is potentially a worthwhile investment but we don't know your environment. If you can justify the investment I would add the switch. And besides it helps the economy. Smiley Wink

-- David -- VMware Communities Moderator
s1xth
VMware Employee
VMware Employee

Dont mess with VLANS unless your core switch has the BANDWITH and connectivity to support it. Go dedicated. Makes life easier and eliminates a point of problems.

http://www.virtualizationimpact.com http://www.handsonvirtualization.com Twitter: @jfranconi
PaulSvirin
Expert
Expert

Vote for dedication too.

Additionally you can tweak iSCSI performance by overriding "auto-negotiation" and manually

adjusting speed settings on the NIC and switch. This lets you

enable traffic flow control on the NIC and switch, setting Ethernet

jumbo frames on the NIC and switch to 9000 bytes or higher --

transferring far more data in each packet while requiring less

overhead. Jumbo frames are reported to improve throughput as much

as 50%.

---

iSCSI SAN software

--- iSCSI SAN software http://www.starwindsoftware.com
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ddockter
Contributor
Contributor

Cool. Now to determine whether that model ProCurve is the right solution. I don't want to spend $1,000's of dollars to do this.

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DSTAVERT
Immortal
Immortal

It looks like a decent switch. You don't need to go overboard. Save some budget for the next enhancement.

-- David -- VMware Communities Moderator
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J1mbo
Virtuoso
Virtuoso

Echoing the comments above, definitely dedicated is the way to go. Since there is only 1 iSCSI device, probably only a basic "good quality" switch is required again as said. Better switches are needed with multiple trays of disks where frame buffers can become a problem with the high throughput from multiple devices.

However the comments above about manually setting port configs I don't concur with. Flow control is a requirement for vmware software iSCSI and your switches should support this and have it enabled on all ports, however once enabled this is offered through the auto-negotiation process. Hence everything should remain auto/auto (speed/duplex) throughout.

Please award points to any useful answer.

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