Hi , I'm currently doing some testing to get more speed from ISCSI targe of Open-E , I observed some things that I would like to share with Open-E team and people's here.I tested on the same hardware SanMelody,Starwind from rocketvision and Open-E 1.23(2763).
Target
Dell PowerEdge 2800
2GB Ram
PERC 4/SC with write-back enable 33GB disk for boot and RAID5 280GB for Local Data
Broadcom 5703 PCI-X 1GB/s
Windows 2003 server for starwind and sanmelody test
Dual-Xeon 3.6
Apple Xraid with 3TB connect over LSI Logic Fiber 2GB/s ( 7202-LXP ) ( for ISCSI Target )
Local bench speed of this setup is 90MB/s burst rate , and 60MB/s constant read speed ( mesure with HDtach) , for the real world test I copied a 2GB files ( 2097MB exactly ) from built-in data hard disk to AppleXraid and it take 30s so this mean approximatly 69.9MB/s real world speed.
If I use Starwind or SanMelody I can copy my 2GB file over ISCSI target and it take from 35s to 40s ( 52MB/s to 59MB/s ) so it close to the maximum of my hardware capacity.
The things that causing me some questions is that Open-E change speed drasticly if file size is over the maximum ram of my system , this is my observation
If I copy the same 2GB files over Open-E ISCSI Target as soon as I reach approximately 3/4 of the file size the speed change drasticly , it take 1m10s to copy it so 29MB/s. Now if I take a 750MB files it take 15s so 50MB/s now close to other target software on same hardware. Its look like Open-E does'nt used RAM's the same way as other target. I don't know but I think it could be a Swap Area problem , when I create a volume on Open-E the swap space of 4GB is put on same vg as target so if I copy a 2GB file my system ram reach is maximum and start to swap but on same volume as the target, now if I copy a 750MB file the system ram is enough to buffer it entirely so this is probably why the speed is the same as other target software , on its part windows 2003 take his boot drive for swap and Open-E is load enterly in RAM so it cannot use his local drive for swapping purpose. Now my question is , do you think that it could be possible to have swap space locate on different vg that the ISCSI target is using? This theory could be apply on any RAM size and FC or ISCSI Target so 1GB Ram mean that file over 750MB in size will start to causing some speed issue also.
Sorry for my english and thanks for your time!
Keven