Hi,
Two weeks ago I upgraded my 3 ESX server from version 3.5 to version 4.0 upgrade 1.
After the upgrade my problems was initiated.
Now I paste the messages from one server (other 2 are the same) :

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
06/04/2010 13.01.36

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
06/04/2010 13.00.51

Successfully restored access to volume 48492a25-003a30a6-fba5-001b211a6d88
(iscsi-storage) following connectivity issues.
info
06/04/2010 12.00.48

Lost access to volume 48492a25-003a30a6-fba5-001b211a6d88 (iscsi-storage)
due to connectivity issues. Recovery attempt is in progress and outcome will be
reported shortly.
info
06/04/2010 12.00.48

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
06/04/2010 12.00.44

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
06/04/2010 11.01.07

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
06/04/2010 10.00.53

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
05/04/2010 18.01.33

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
05/04/2010 18.00.37

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
05/04/2010 15.01.59

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
05/04/2010 12.02.30

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
05/04/2010 2.01.28

Lost connectivity to storage device
t10.963534359400000000000000100000003800000050000D F0. Path vmhba33:C0
:T0:L0 is down. Affected datastores: "iscsi-storage".
error
04/04/2010 22.29.52

.....

I don't know and 1 time a week the servers are blocked and I have to restart all ESX server.

how is possible ?

thank's a lot in advance.