On Wed, 2011-09-14 at 19:30 +0530, Abhilash Sankar - ERS, HCL Tech wrote: > Hi all, > > My name is Abhilash, I am new to this community, I am trying to do a performance study of LIO-iSCSI and SCST using robocopy (I/O Tool). > I have successfully ported LIO to my Debian OS. Based on my initial analysis, SCST had shown a better write performance than LIO. > > Read performance seems to be almost similar for both the stack. But write performance for file based LIO-iSCSI has degraded more than 50% > while compared to SCST stack in my setup. > > I am using LIO 4.0, file based IO and Windows 7 initiator. > > It would be much helpful if anyone could give me some suggestion to improve the LIO write performance. > Hi Abhilash, By default target_core_file.c is using O_SYNC to ensure that WRITEs are written directly to disk before acknowledging back to the SCSI client. This will have a considerable effect on FILEIO WRITE performance, but is done by default to ensure proper data integrity in the face of target power loss. You may want to double check the filp_open() flags with SCST to ensure that you are comparing 'apples to apples' here. Optionally you can try disabling O_SYNC with target_core_file.c via rtslib with the class FileIOStorageObject:_set_buffered_mode() mentioned here: http://www.risingtidesystems.com/git/?p=rtslib.git;a=blob;f=rtslib/tcm.py;h=4da49b0f4a4aea9a1eebed23d457181085a2d03d;hb=HEAD#l975 --nab -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
