iSCSI Target Query

[thechicco]

Hey all,

I have configured some LUN’s on our EqualLogic PS300E but I am a bit confused about the ESX iSCSI requirements and limitations, particularly the maximum number of iSCSI targets (which I believe is 8).

Is this maximum in regard to targets counted as storage devices (so I could have a maximum of 8 x PS300E’s say) or LUN’s (I have 5 at the moment, ie. prd-vmfs-data-01, data-02, etc).

Sorry if it sounds newbie (1st time with an iSCSI) but in VI - Storage adapters it has my LUNs but has "SCSI target X" next to them.

Cheers

[GCR · Accepted solution]

Hello,

As I know so far you don't have a real limit of iSCSXI targets, but there are limits for number of LUNs (256) or for different paths (32) or storage iSCSI Adapters (2) as you can see on http://www.vmware.com/pdf/vi3_301_201_config_max.pdf .

So I believe that your concern should be around number of LUNs and that is 256 per ESX server.

Hope that this will help you.

Cheers,

Goncalo

[thechicco]

Good link, cheers Goncalo.

[chrisy]

In iSCSI terms a 'target' is what you tell the ESX server to connect to. On EqualLogic, you connect to a storage group using the group IP address. So - although I don't have the opportunity to test - you might be able to connect to 8 groups, which is dozens of Eql boxes potentially. If so that should be a limit of over 500T (before RAID) which is, err... sufficient.

Chris Y

[thechicco]

Hey Chris.

Yep that's what I'm assuming as well. My understanding is that EqualLogic array 1 (group IP) is iSCSI target 1, EqualLogic array 2 (group IP) is iSCSI target 2, etc.

However when in VI - Storage Adapters, vmhba1 has "Targets: 4" which equals the amount of LUN's I have defined. I am just uncertain whether it's counting these as iSCSI targets OR my EqualLogic group IP as an iSCSI target.

Sorry if it sounds confusing, I think I've confused myself!

Cheers,

Dale

[acr]

Contrasting Info..!!

Max iSCSI Target for ESX 3 is 8

see Page 8

http://www.vmware.com/pdf/vi3_iscsi_cfg.pdf

Also

[url=http://kb.vmware.com/vmtnkb/search.do?cmd=display

KC&docType=kc&externalId=9565423&sliceId=SAL_Public&di

alogID=13677570&stateId=0%200%2013673765&doctag=Author

,%20KB%20Article]129 LUNs Presented iSCSI Initiator[/url].

[tsherbak]

Hi All,

The iSCSI target limit in ESX currently is 64 targets. This is a hard limit with the iSCSI sw initiator (actually you max out w/ ~72 targets configured). With the iSCSI hw initiator (QLogic HBA), this is a soft limit (you max out at 256 targets configured).

Each volume (LUN) in an EqualLogic group is also a target. I.e., there is a one-to-one mapping of volume/LUNs to targets. Why is this so? In contrast to FC, where a target is effectively a fixed controller with multiple LUNs, with virtualized iSCSI SANs, volumes can seamlessly migrate or span across controllers. So, its desirable that the address of the volume be a 'virtual address' that can easily be served by resources from across the virtualized storage pool. Thus, the close association between the 'virtual' target address and the volume.

Tim

[tsherbak]

I believe this doc is out of date:

http://www.vmware.com/pdf/vi3_iscsi_cfg.pdf

The HCL

http://www.vmware.com/pdf/vi3_san_guide.pdf

has previously been updated to reflect 64 targets.

[acr]

Tim,

Nicely cleared up.. 64 Targets it is..

[thechicco]

Tim, Tony, many thanks for clearing it up!

Dale

[acr]

Hey Dale, Happy EQLing..!!

[chrisy]

I thought this was all settled, but looking at the HCL (link as above) it lists 15 targets (?)

I've checked the HCL for 3.0.x and 3.5 and they're the same.

What's the story? Is the doc wrong, and the soft / hard limits are 64 / 256 as above? Or has there been an unwelcome change, and we really can only create 15 LUNs and be supported? Hopefully I'm just having a bad day, and there's a '64' right there in the docs somewhere, and I missed it!

--

Chris

[tsherbak]

Page 41 of this document refers to 64 targets as the maximum number of iSCSI targets.

This is a hard limit with the iSCSI sw initiator. With the iSCSI hw initiator (QLogic HBA), this is a soft limit (you max out at 256 targets configured).

[elgordojimenez]

hello All,

I searched that link http://www.vmware.com/pdf/vi3_san_guide.pdf and when i look for maximum storage specifications supported i can not see the 64 anywhere. i can only see Maximum number of targets per HBA: 15. i am following the book by Chris McCain for vi3 for my vmware studies and whilst searching the forums came across with this thread. is there any other document?

cheers.