Hi Mike and List,

Thanks for the reply.

On Wed, May 21, 2008 at 12:28 AM, Mike Christie <[EMAIL PROTECTED]> wrote:
> Shrey wrote:
>> Hi Mike,
>> Thanks for you reply. Please find my reply inline.
>> On May 19, 11:04 pm, Mike Christie <[EMAIL PROTECTED]> wrote:
>>> Shrey wrote:
>>>> Dear All,
>>>> I started using/studying open-iscsi recently. I was wondering if there
>>>> is any hard-coded limit to number of targets devices that can
>>>> discovered per iSCSI target? Is there any hard-coded limit on the
>>>> number of LUNs supported per target device (assuming that somehow HBA
>>>> on iscsi target doesn't present any limit) ?
>>> As others pointed out there is a module param for the max lun for
>>> iscsi_tcp, but that should actually be limited by a libiscsi/scsi-ml
>>> limit. libiscsi uses a function named int_to_scsilun in
>>> drivers/scsi/scsi_scan.c and as you can see that only implments 2
>>> levels. libiscsi/iscsi_tcp also does not do the device scanning (the
>>> iscsi layer only finds the targets) so we are limited by scsi_scan.c. To
>>> get the limits for that do "modinfo scsi_mod".
>> Ok, that gives me something to thing/experiment about. Thanks
>>> There is also a limit on the number of targets. Because we allocate a
>>> scsi_host per session, and the scsi layer uses a unsigned short for the
>>> host number the number of targets is 2^16.
>> That would mean 65536 devices. But I get stuck far below that - just
>> about 90 targets.
> If you are using 869.* then the problem is most likely on the IET side.
> Like I said before I think you need to upgrade. I had the same problem
> when I was testing my fixes for lots of targets support.
> Oh yeah, I said this in some other mail, but will say it here so people
> can search for it. There is another target limit and that is the number
> of files a process can have open. We open a tcp socket for each session
> and we do a session to each target portal. We also will open other files
> so the exact number is not known. I think it is probably around 4000. I
> do not have a setup that supports that many targets yet to know exactly
> though. Let us know what you find out.

Hmm, that sounds quite a large value as against what I am
experiencing. I will try and find out what is happening in my case -
probably the iscsi-target is acting like some kind of bottleneck (the
max size of PDU is my initial guess) - or may be I am missing

Nevetheless, thanks for the info - i really appreciate your help.

>> Are some parameters which I am missing which I need to configure or
>> take care of?
>> I tried tinkering "node.conn[0].iscsi.MaxRecvDataSegmentLength =
>> 65536" but there was no difference. This actually is making me think
>> that target is acting as a bottleneck.
> That is just for normal sessions. You would want to set
> discovery.sendtargets.iscsi.MaxRecvDataSegmentLength

Oops - I should have noticed. Thanks once again. I will try tinkering with this.

> but like I said that will not completely fix the problem.

Well, this should give me something very good to start with. I will
post whatever my finding are (as soon as I find something ;) ). Thanks


You received this message because you are subscribed to the Google Groups 
"open-iscsi" group.
To post to this group, send email to open-iscsi@googlegroups.com
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at http://groups.google.com/group/open-iscsi

Reply via email to