Online extension of iscsi target

For online resizing of connected iscsi target, we have to extend underlying device first, this way, for example:

lvextend /dev/guests3/target_iscsi_cestadomu_dsa -L+40G

Now, we have to tell this info to SCST and to iSCSI initiator (using vdisk DEVICE name) :

scstadmin -resync_dev iscsi.cesta.dsa

SCST send info to initiator:

Jun 19 14:09:04 backuphost1 kernel: [ 8982.046784] [1737]: dev_vdisk: vdisk_resync_size:3381:New size of SCSI target virtual disk iscsi.cesta.dsa (fs=122876MB, bs=512, nblocks=251650048, cyln=122876)
Jun 19 14:09:04 backuphost1 kernel: [ 8982.047050] [1737]: scst_capacity_data_changed:1447:CAPACITY DATA CHANGED (dev ffff880827956400)
Jun 19 14:09:04 backuphost1 kernel: [ 8982.047248] [1737]: iscsi_scsi_aen:3608:SCSI AEN to sess ffff8808199aa000 (initiator iqn.1991-05.com.microsoft:dsa.cestadomu.local)