Comments 3 Posted In Red Hat Enterprise Linux "How to verify that the disk is iscsi3 persistent compliant" Latest response 2018-09-08T07:25:24+00:00 "How to verify that the disk is iscsi3 persistent compliant" zh Started 2017-05-31T05:31:35+00:00 by zahid haseeb Community Member 92 points Log in to join the conversation Responses Sort By Oldest Sort By Newest MK Guru 2032 points 31 May 2017 11:19 AM Matti Kurkela Do you mean SCSI-3 persistent reservations? That is a SCSI feature that can be used with all SCSI-based disk interface technologies, including iSCSI. The SCSI-3 persistent reservations features of a disk can be queried and tested with the sg_persist command, which is included in the sg3_utils RPM package. You can attempt to read the persistent-reservations capabilities of a disk/LUN with the "sg_persist -d /dev/ -c" command. If the disk/LUN won't support SCSI-3 persistent reservations, the commands will respond with a "command not supported" error message: [root@localhost ~]# sg_persist -d /dev/sda -c ATA VBOX HARDDISK 1.0 Peripheral device type: disk PR in (Report capabilities): command not supported If the disk/LUN claims to support SCSI-3 persistent reservations, you'll get a longer response: # sg_persist -d /dev/sde -c IBM 2145 0000 Peripheral device type: disk Report capabilities response: Compatible Reservation Handling(CRH): 1 Specify Initiator Ports Capable(SIP_C): 0 All Target Ports Capable(ATP_C): 0 Persist Through Power Loss Capable(PTPL_C): 1 Type Mask Valid(TMV): 1 Allow Commands: 0 Persist Through Power Loss Active(PTPL_A): 0 Support indicated in Type mask: Write Exclusive, all registrants: 1 Exclusive Access, registrants only: 1 Write Exclusive, registrants only: 1 Exclusive Access: 1 Write Exclusive: 1 Exclusive Access, all registrants: 1 The above commands are sufficient to verify if the disk/LUN claims to support SCSI-3 persistent reservations or not. If you actually need to verify that the reservations are implemented according to spec, you'll probably need to present the disk/LUN to at least two systems and then use the sg_persist command to set up all the various types of reservations one at a time from one system, and then try and access the disk/LUN from the other system, and verify that the reservations block either write access or all access to the disk/LUN from the system that is not currently holding the reservation. CA Newbie 7 points 10 July 2017 9:49 PM Claudiu Avatamanitei Great piece of information, thank you! KY Newbie 7 points 8 September 2018 7:25 AM Kranti Yadhati Useful info. Thank you!