In release notes it states that when upgrading to this version it is recommended to remove LV's and then recreate them due to the Block IO - 1.23 is File IO. You will have to save your data. Although you don't have to.

* IMPORTANT : Since ver 1.30 New iSCSI default volume creation is done in block-IO in contrast to the older version that was file-IO.
In order to create new iSCSI volume in "old" file-IO mode, please switch the default in console tools menu: ctrl-alt-w --> Tuning options-->iSCSI daemon options-->iSCSI volume type.
Block-IO mode is about 30% faster then File-IO and the target volume size is exactly equal to defined iSCSI volume size (in file-IO the target size is a bit smaller then defined iSCSI volume size).
Additionally, initialization is no-longer required as with the old file-IO volumes.
In order to migrate your data from the file-IO to block-IO volume, the data must be backed up from the existing iSCSI volumes and then restored into newly created iSCSI volumes.
NOTE: please verify data integrity prior to deleting old iSCSI volumes.
Volume replication is only possible between to similar volumes (e.g. block-IO <-> block-IO or file-IO <-> file-IO). Volume replication between old file-IO and block-IO volumes are NOT possible.