From: "Simon Grinberg" <[email protected]>
To: "Michael Pasternak" <[email protected]>
Cc: "engine-devel" <[email protected]>
Sent: Monday, October 22, 2012 10:50:02 AM
Subject: Re: [Engine-devel] alias in disk instead of name
----- Original Message -----
From: "Michael Pasternak" <[email protected]>
To: "Simon Grinberg" <[email protected]>
Cc: "engine-devel" <[email protected]>
Sent: Monday, October 22, 2012 8:58:25 AM
Subject: Re: [Engine-devel] alias in disk instead of name
On 10/21/2012 06:13 PM, Simon Grinberg wrote:
----- Original Message -----
From: "Michael Pasternak" <[email protected]>
To: "Simon Grinberg" <[email protected]>
Cc: "engine-devel" <[email protected]>
Sent: Sunday, October 21, 2012 4:56:33 PM
Subject: Re: [Engine-devel] alias in disk instead of name
On 10/21/2012 04:15 PM, Simon Grinberg wrote:
----- Original Message -----
From: "Michael Pasternak" <[email protected]>
To: "Simon Grinberg" <[email protected]>
Cc: "engine-devel" <[email protected]>
Sent: Sunday, October 21, 2012 3:48:46 PM
Subject: Re: [Engine-devel] alias in disk instead of
name
On 10/21/2012 03:36 PM, Simon Grinberg wrote:
----- Original Message -----
From: "Michael Pasternak" <[email protected]>
To: "engine-devel" <[email protected]>
Sent: Sunday, October 21, 2012 12:26:46 PM
Subject: [Engine-devel] alias in disk instead of name
The problem we caused by using alias in disk instead
of
name
is
break
of search-by-name paradigm
in engine.search dialect, not sure why we do not want
forcing
disk
name to be unique [1],
but lack of "name" in disk search is does not look
good
in
my
view.
thoughts?
[1] can be easily achieved via appropriate
can-do-action
verification.
Names by definition are not unique IDs,
they do, otherwise /search wasn't effective, remember
users
not
exposed to entity id, all entities fetched by-name, so
names
has
to
be unique.
Yap that is what we do with many entities, and it causes
problems.
But with disks it is multiplied
thus it should not be enforced.
What would be the auto naming conversion to ensure
uniqueness
with
plain text?
not sure i follow, i'll assume you refer here to empty
name, -
you
cannot have an
entity with no name.
Well you create a new disk - do we want to enforce the
user
to
provide a unique disk name/alias for every disk he
creates?
This will drive the user crazy. This is important even
for
user
only for floating/shared disks. For any other disks user
does
not
care if it's disk1, hd1, whatever. For these kind of
disk,
it's
just a VM disk and the user does not care if in all VMs
this
is
called disk 1 - so why bother him?
from the same reason we have unique
clusters/datacenters/networks/templates/etc...
Networks, DataCenter, Clusters, templates - are in order of
magnitude less then the number of disks.
And you name once and use many.
As for VMs - well it's may take that we should not force
uniqueness
either ( you can warn though )
you cannot have two vms with same name in same domain ...
I didn't say that in a domain you are allowed to have two
guests
with
the same hostname, I've said engine should allow for having
duplicate VM names.
You are assuming that the VM name is identical to the guest
host
name.
For many this is the case, for other it's just an alias/name
given
in
oVirt.
Actually for the cloud, this is mostly going to be the case and
worse, you are blocking different tenants from having the same
VM
name just because you are assuming that VM name = guest
hostname.
For disks, well number is >= VMs to >>>= VMs
Name by definition is mostly interesting in many cases only
within
the VM, and we don't even have a way to correlate disk
alias
to
the internal name in the VM. In many cases as said before,
a
user
won't care about the name/alias if it is always attached to
the
same VM. A user will rather look the VM and then list it's
disk.
So actually I'll be better off with vm1.disk1 vm2.disk2
then
unique name per disk (PS AFAIK) this should be the default
suggested name by the UI, but then changing the VM name
will
break
this (yes, I know it's not possible ATM, but many people I
know
requested for that).
So I as user will prefer that all the disks that created
from
a
template will have the same name as the original template,
and
then to be able to search by (vm=name, disk=name) thus I
can
access easily the same disk for the VMs.
On the other hand for others, as you've mentioned
(especially
for
floating and shared disk) the name/alias may be of
importance,
uniqueness may be very important.
any disk can become shared.
Then when you make it shared then bother to give it a
meaningful
alias
All that I'm saying that we can't force it's not that
uniqueness
in
never desired.
simon, you missing the point, i was talking about /search,
search is available only at /api/disks (i.e shared disks,
vm/template.disks is
irrelevant to this discussion)
Nope I do not, but I think that our perspectives differ.
You are looking at it as strictly design issue. You have a
collection
of entities and you want a human readable search, thus you are
trying to force (rightfully) from your point of view a unique
alias/name for those.
I taking the end user perspective, and user experience
1. Majority of the disks have no meaning outside of a VM scope.
2. There are fractions of the disks that are usually shared
(this
is
the nature of shared disks)
3. There are fractions of floating, most of the floating will
be a
transient state, while you are moving disks around.
What I'm trying to say that forcing a user to provide a unique
name
per disk is a huge bother.
And again in the multi tenancy case, you can't enforce a unique
alias
in the system.
What will you say to the user in the error message?
Sorry you can't use this alias since another user that is
sharing
the
system with you already provided that name? And yes we know you
can't see that other disk, and it you don't care about the
other
user, but still you can't use your alias since this is how our
platform designed.
The meaning is that you must allow a for a more sophisticated
search.
Yes even in the context of the disks tab. Disks are not really
stand
alone entities, and if we keep to strict conventions like - in
any
collection an entity name must be unique, then you are making
the
system hardly usable for many users.
So a search in disks should include other 'properties' (and yes
I
know those are not disk properties, but this is how a user will
look
at it) like owner,quota,vm,storage domain, etc.
To some up - what should be unique are UUIDs of an entities,
and
infrastructure entities names (within the same scope) - all the
rest
must not.
Would you change these on import/export?
would you mind elaborating on this?
Yes,
You are already facing a problem when importing VMs that
already
have the same name, now you increasing the problem for
disks
that
have the same alias. for same name we force clone if you
want
to
import. Why for clone just because of a disk alias (this
implies
collapse snapshots ATM) or even bother the user with
renaming
disks that he does not care about the name so he just
gave
disk
1,
2, 3 and so on?
i see your point, but then we leave no option for the user
to
locate
the disk,
simply because he doesn't have unique identifier,
just imagine user A creating disk and calling it X,
then user B creating disk and calling it X, they on
different
domains etc., and now both want to use disk X,
how they can figure out which one to pick?, by SD, by
size?
agree
this is doesn't look well..., even more than that -
someone
may
call
this "bad design"...
This is why the search should accept more then the name.
Example (vm=name, disk=name/alias)
Example (dc=name, disk=name/alias)
Example (sd=name, disk=name/alias)
it's not about accepting both name/alias, it's about missing
ability
to identify your resource in collection.
For floating/shared on the same SD/DC/VM I would suggest a
warning
if there is a duplicate in the system - not enforcement.
ok, lets assume we WARN user that his disk's name is not
unique,
how
user will pick the unique name?
implementing own code checking if new name (he wants to use)
is
unique or not?
- this is business logic, not user's prerogative.
There is a difference between best practice and being
enforcing
up
to the level that it annoys some of the users.
simon, when you register to email, you have to try N times
till
you
find unique username,
is it convenient? absolutely NO, is it annoying? YES, but you
forced
doing that so
system will be able to identify you,
it's no different in any way, good software protects
user/itself
even
in cost of convenience,
bottom line
===========
- i think as long as disk not shared/floating it can have any
name
- in a minute disk designation changed to shared, name
uniqueness
should be forced (by the engine)
- when importing vm with shared disks, name uniqueness should
be
forced
- when creating vm from template with shared disk, name
uniqueness
should be forced
- alias should be changed back to name (in sake of
consistency)
- /api/disks collection should support searching disks by
name
(in
sake of consistency)
thoughts?
Please look at the previous comment, that just can't work in
the
multi-tenancy case.
Name should not be unique, the warning is for the admin only,
from
the user portal a warning should be issues only if the user
provides
same name twice.
--
Michael Pasternak
RedHat, ENG-Virtualization R&D
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--
Michael Pasternak
RedHat, ENG-Virtualization R&D
_______________________________________________
Engine-devel mailing list
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