Environment:
scsi-target-utils-1.0.14-2.el6.x86_64 on RHEL6.1

I updated the /etc/tgt/targets.conf with:
scenario a - 250 targets, each target contains one lun (lvs as backing store)
scenario b - 1 target with 250 luns (lvs as backing store)

Then I tried to restart tgtd or perform "tgt-admin --update ALL", the tgtd restart failed and the "tgt-admin --update ALL" fails every time with the same error message but each time on different target, it seems that each "tgt-admin --update ALL" can deal with only ~7-10 new target which it opens successfully and then it fails.

For the case of 250 targets - I need to run "tgt-admin --update ALL" ~30 times for all devices to be open.

[root@lion ~]# for i in `seq 1 10` ; do tgt-admin --update ALL ; done
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 60 -T script121
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 74 -T script134
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 77 -T script137
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 78 -T script138
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 92 -T script150
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 93 -T script141
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 110 -T script167
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 111 -T script159
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 113 -T script17
exited with code: 22.
tgtadm: this target already exists
Command:
	tgtadm -C 0 --lld iscsi --op new --mode target --tid 114 -T script170
exited with code: 22.
[root@lion ~]#