General Discussion

Hi

I'm creating a DP-VOL using the RestAPI (PF-Rest , built-in to the array)

REQUEST:

POST base-URL/v1/objects/ldevs

REQUEST-BODY:

{
 "ldevId": 1024,
 "poolId": 0,
 "byteFormatCapacity": "1T",
 "dataReductionMode": "disabled"
}

After creating the DP-VOL, which statement is actually
true (based on fact ... not based on intuitive feeling, opinion or guess):

Statement A:

After creating a new DP-VOL with the RestAPI,
there is zero reason to format the new DP-vol.
Just, go ahead and present the DP-Vol to host-groups
and use it.

Staement B:

After creating a new DP-VOL with the RestAPI,
you should format the new DP-vol before using it.

My guess ( could be wrong ... that's why I'm asking):

I think that Statement A is true. My understanding is:
Formatting a BASIC-LDEV ( aka POOL-VOL ) is essential since
some media error detection is performed.
Based on experience (... using SVP StoNav GUI ), this formatting
occurs automatically when a DP-POOL is created from BASIC-LDEVs/POOL-VOLs.

HOWEVER, formatting a DP-VOL performs no media checking, it
simply returns a DP-VOL's used capacity to the DP-POOL,
thus it would make no sense to format a NEW DP-VOL since
it has no used capacity. 

The reason I'm asking: In the E590 RestAPI manual, the section on
formatting volumes appears immediately after the section on creating
volumes. The manual does not contain any guidance on the question
of formatting or not-formatting new DP-VOLs

Thanks

Andy

------------------------------
Andrew Romero
Storage Administrator
------------------------------

Not having ever used REST to configure storage, my general modus-operandi is to create PG's; carve LDEVs (format them) and then place them (whilst undergoing or waiting format) into the HDP pool as pool vol's.

------------------------------
Albert Hagopian
Software Development Engineer - Specialist
Hitachi Vantara
------------------------------

> -----Original Message-----
> From: Albert Hagopian via Hitachi Vantara <mail@connectedcommunity.org>
>
> Not having ever used REST to configure storage, my general modus-operandi is to create PG's; carve LDEVs (format them) and then
> place them (whilst...

Hi

Yes, when using StorageNavigator (running on the SVP ), my experience has been that, yes,
Basic-LDEVSs ( aka "pool vols" ) do get formatted. Format is kicked off automatically when
One creates a DP pool using the "pool vols". After the pool creation and the formatting
of the basic-LDEVs ( "pool-vols" ) is complete, then Its time to create and, present to hosts,
Dynamic Provisioned LDEVS ( aka "DP-vols" ).

I have never formatted DP-vols; so, when the
RestAPI manual discussed specifically how to format DP-vols ( with no info on when one would
actually want to do that ) ... I thought to my self :
- Oh no ... have I been doing it wrong all these years ?
- Rats now my RestAPI code will need to use threads or multiprocessing to
properly keep sessions alive while long-running format ops execute.

So I submitted the question to the community ... do I need to format new DP-vols ?

I also opened an "info" case and asked another Hitachi staffer the same question:

Official Answer: There is no need to format newly created DP-vols..period

So back to RestAPI coding.

I'm done with my code for managing sessions and locks and also my code for managing host-groups and host wwns in host groups, I just have to finish
DP-vol creation, expansion, and presentation and I'm done. I will post some of the code to the community soon.

Have a great week-end

Andy


Original Message:
Sent: 4/28/2023 2:17:00 PM
From: Albert Hagopian
Subject: RE: Rest API question on the need to format newly created DP-VOLs

Not having ever used REST to configure storage, my general modus-operandi is to create PG's; carve LDEVs (format them) and then place them (whilst undergoing or waiting format) into the HDP pool as pool vol's.

------------------------------
Albert Hagopian
Software Development Engineer - Specialist
Hitachi Vantara
------------------------------

Hi Andrew,

Statement A is correct, after creating a DP volume through PF or CMREST you don't need to format them, you can directly map them to the host group.

------------------------------
Prasenjit Chatterjee
Test Engineer
Hitachi Vantara
------------------------------

Hi Andrew,

Statement A is correct, after creating a DP-vol you can directly map them to the host group.

------------------------------
Prasenjit Chatterjee
Test Engineer
Hitachi Vantara
------------------------------