ISCSI experts ?

[jetlee]

Hi Guys

Looking for an idea to try, so calling all ISCSI experts..

Getting a wierd ISCSI behaviour .. and Im just stumped, so keen to try anything I havent already tried ...

ISCSI Target - Debian, ISCSI Initiator Win 8.1 (MS Default initiator)
When the machine boots up with a primary physical harddisk, and I attach the ISCSI target as D drive, I get good enough speed on ly LAN (5 Disk Raid 5 mdadm) (90MB/s read and write for 512K files)

The minute I remove the primary, and PXE Boot into ISCSI as the primary disk (iPxe), Tests run at aroun 12MB/s

A Wireshark trace shows that when the ISCSI disk is primary, my network packets are shown to be sent to my ADSL Router (which is also my default gateway) which is only 10/100 (hence I believe explaining the drop in speed). When I try to perf test a secondary ISCSI Disk (ie D Drive), all packets are correctly routed to my Gigabit switch.

When doing the same test using a Debian ISCSI Initiator, the primary disk / secondary behave perfectly (ie 90MB/s read and Write whether the disk is primary or secondary)

Anybody got any bright ideas (besides a new gigabit router )

 

[IguBu]

When you say attach as d drive - is the debian a vm running on the windows or a physical device attached (another pc)? What i'm after is what connectivity exists between debian/win81 as your first part when the speed is good. I see mention of a raid 5 set - NAS somewhere?

If it's all on the same LAN - leave out the gateway on the isci init. network settings and see what happens.

If they are physical devices connected with together with the 100Mb router - you will need a new switch

You get linksys 5-port Gig switches for around R500 - so not too bad I think.

http://www.pricecheck.co.za/offers/73970322/Linksys+Se2500+5-port+10_100_1000mbps+Switch

Worth the R500 i think

B

 

[jetlee]

Hey

They are 2 separate machines, linked on the same 8 port gigabit switch, the ADSL router is 2 extra hops away ..

The target is a Linux (Debian) machine running 5 disk raid 5
The initiator is a separate PC runing windows 8.1
Connected to the same gigabit switch

The nature of ISCSI is that it presents as a physical disk (ie SAN), vs a NFS share which is presented as a share (ie NAS).. so when I attach it to the physical machine (using the initiator), it can connect as any drive, as it presents as a disk in the "disk management" interface.. basically .. if I connect it and assign it as a D drive (ie booting off a physical disk), it is super fast.. BUT .. when I take the same machine and do nothing else but remove the physical disk, it will boot (no physical disk .. ie network boot via ipxe) and present the ISCSI disk as a C: drive, which then is very slow ..

so to clarify ... same PC, same connectivity .. the only difference is that I remove the physical disk .. and all of a sudden my routing wants to go to my ADSL routers MAC address .. according to Wireshark ..

Hope that makes sense

 

[Sinbad]

Check subnet mask on your iscsi booted image.

 

[jetlee]

subnet mask is exactly the same as the disk image, the iscsi booted image, is created (imaged) from the physical disk, that is also used in the boot tests.

255.255.255.0

Both boots have the same ip /subnet / def gateway