Is there any expert would like to explain how "fast IML" works in VMAX3? Why can it upgrade Hypermax OS in only 10s(2s in some documents)?
The IML of directors and timing can always be a "it depends"
Couple of points though so we may understand it better.
An IML in VMAX3 should be none too different than it was in VMAX2 , as essentially Hypermax OS is essentially built on the legacy code that was microcode so essentially almost the same rules or behavior will be seen.
Typically an IML will happen when we are going from one code to the next or a config change done through a binfile change.
The timing of the IML then depends on what is happening with the codes going from one code to the next and what the developer is changing within the array code, so an IML in one code code may not be the same length as an IML in another code jump.
You might see and IML taking 10s and then the developer will go back and make changes to the code or fix and now the same IML will take 2 seconds.
That being said, the vmax3 because of its dynamic backend we should see very few FAST IMLs.
Any changes the customer can do through the symcli or unisphere will typically be on the dynamic back end which will not result in a fast iml.
A binfile change or code change will probably incur a FAST IML and this should typically take 2 - 3 seconds or at least that is the expected timeframe, longer than this we could start seeing host timeouts depending on the sensitivity of the Host.
Hi, JimmyNyhan, thanks for your answer!
I saw a short explain for "fast IML" - "A fast IML is a reset of the director where a full IML reloaded the code from EEPROM" in the link "What is ZAP and why do we use it?". So a fast IML is really a full IML, except that it reloads the code from EEPROM? I really can't understand it.
There are two different type of IML's that a Symmetrix director can go thru. The first type is FD which is also know as a fast IML and an FE which is know as a full IML.
There are 2 different types of IML's, one called a quick IML or a FD of the director. This is done when there are changes in the devices on directors or moves made that you want all directors to know about. Say a Control Center add or SDDR move. The other is a full IML, which was more than likely yours, and that is called a FE of the Director.