Bug#586957: lvm2: miscellaneous improvements for the lvm(8) manpage

Christoph Anton Mitterer calestyo at scientia.net
Thu Jun 24 11:34:53 UTC 2010


On Thu, 24 Jun 2010 01:44:58 +0100, Alasdair G Kergon <agk at redhat.com>
wrote:
>> It seems that the current "Where a list of VGs is required but is left
>> empty, a
>> list  of  all VGs will be substituted." is also true for LVs (checked
it
>> with
>> lvdisplay, which seems to lists all LVs).
> Yes
k, so that part of the patch already applies.


>> - Also clarifies, that @ is only used
>> when referencing tags, not when setting them (i.e. that it's just part
>> of the
>> string name).
> You should always be able to use @ to indicate a tag.
> It's optional in places where there's no ambiguity.
Well I guess,.. forget that one (and drop the related part of the patch).
In the beginning I had the idea that tags would share the same namespace
as VG/LV names and just therefore you suggest the use of @, which then
would have no special meaning at all.... but it's apparently stupid and
they have separate namespaces, right?


>> 1) Should we explicitly mention, that VG/LV names as well as tags are
>> case-
>> sensitive (or is A-Z a-z) enough.
> No harm in doing that - I just assumed people would assume that...
I think it's rather clear, but you may add it if you want :)
I'm a perfectionist in such things ;)


> "one stripe can have several extents" is imprecise to me.
Ok,.. I still didn't get it:
We have extents, chunks (with snapshots) and stripes (when doing
striping... e.g. -I with lvcreate), right?
So I though, extents are the biggest ranges, and can be further divided in
chunks (for snapshots) and stripes, but not vice versa, e.g. you cannot
have multiple extents in one chunk or stripe.
True so far?
And I further understood that all this must always align, so
extentsize/chunksize = integer AND extentsize/stripesize = integer, right?

So now back to your example:
> Given A1 A2  and B1 B2  as two stripes of two extents, and space to be
> allocated when extending:  A4 and B4,   cling ensures you get A1 A2 A4 
> and  B1
> B2 B4  instead of A1 A2 B4  and  B1 B2 A4.
> 
> "New extent (A4) on the same PV as existing extents (A1 A2) in the same
> stripe."
Which is exactly what?
A (so A1 and A2 together) is an extent? And B (so B1 and B2 together) is
an extent, right?
And A1 and A2 are two stripes within extent A   and  B1 and B2 are two
stripes within extent B, right?
So the stripesize is exactly extentsize/2 ?

Ok,.. now I'm stuck... ^^


Cheers,
Chris.





More information about the pkg-lvm-maintainers mailing list