[somewhat OT] I just discovered that Stratis uses XFS.

[somewhat OT] I just discovered that Stratis uses XFS.

[Emmanuel Florac]

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Hi all, 
in fact I just discovered that Stratis exists :)
(https://stratis-storage.github.io/relnotes/relnotes-1.0.html) ( details
on https://lwn.net/Articles/755454/)

Reading the FAQ (https://stratis-storage.github.io/FAQ.html) I see that
it uses XFS as a filesystem layer. Furthermore it seems to come from
RedHat. What are the relations with the future XFS capabilities that
Dave (IIRC) demonstrated recently?

Sorry for the OT message :)
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Re: [somewhat OT] I just discovered that Stratis uses XFS.

[Emmanuel Florac]

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Le Tue, 2 Oct 2018 16:25:30 +0200
Emmanuel Florac <eflorac@intellique.com> écrivait:

> Hi all, 
> in fact I just discovered that Stratis exists :)
> (https://stratis-storage.github.io/relnotes/relnotes-1.0.html)
> ( details on https://lwn.net/Articles/755454/)
> 
> Reading the FAQ (https://stratis-storage.github.io/FAQ.html) I see
> that it uses XFS as a filesystem layer. Furthermore it seems to come
> from RedHat. What are the relations with the future XFS capabilities
> that Dave (IIRC) demonstrated recently?
> 
> Sorry for the OT message :)

Oh, and what about the probable constant use of xfs_growfs? Stratis
seems to create all filesystems with a size of 1TB, and extends them as
needed from there. However that means that a filesystem could
potentially be expanded many times, which, as I understand it, is very
suboptimal or worse, can lead to problems (inode allocation, AGs
count and structure, etc).

-- 
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Emmanuel Florac     |   Direction technique
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Re: [somewhat OT] I just discovered that Stratis uses XFS.

[Eric Sandeen]

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On 10/2/18 9:37 AM, Emmanuel Florac wrote:
> Le Tue, 2 Oct 2018 16:25:30 +0200
> Emmanuel Florac <eflorac@intellique.com> écrivait:
> 
>> Hi all, 
>> in fact I just discovered that Stratis exists :)
>> (https://stratis-storage.github.io/relnotes/relnotes-1.0.html)
>> ( details on https://lwn.net/Articles/755454/)
>>
>> Reading the FAQ (https://stratis-storage.github.io/FAQ.html) I see
>> that it uses XFS as a filesystem layer. Furthermore it seems to come
>> from RedHat. What are the relations with the future XFS capabilities
>> that Dave (IIRC) demonstrated recently?
>>
>> Sorry for the OT message :)
> 
> Oh, and what about the probable constant use of xfs_growfs? Stratis
> seems to create all filesystems with a size of 1TB, and extends them as
> needed from there. However that means that a filesystem could
> potentially be expanded many times, which, as I understand it, is very
> suboptimal or worse, can lead to problems (inode allocation, AGs
> count and structure, etc).

First, a disclaimer: I'm not a Stratis expert.

None of Dave's fancy new tricks are in Stratis, because right now Dave's
fancy new tricks are pretty much just in his lab.

As for the growfs, that's a little bit of a concern - in general, the "start
small and grow" worry is that we'll have a bazillion tiny AGs in the result.

But if Stratis starts at 1TB it's not terrible; I'd need to look and see how
many AGs get created (probably 4?) and if so, 250G AGs are not /too/ granular.
If it's creating a lot more smaller AGs, that could become an issue if it gets
grown to a very large size.  IOWs the growfs concern is mostly about the
resulting AG size & AG count.

-Eric


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Re: [somewhat OT] I just discovered that Stratis uses XFS.

[Emmanuel Florac]

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Le Tue, 2 Oct 2018 10:05:42 -0500
Eric Sandeen <sandeen@sandeen.net> écrivait:

> But if Stratis starts at 1TB it's not terrible; I'd need to look and
> see how many AGs get created (probably 4?) and if so, 250G AGs are
> not /too/ granular. If it's creating a lot more smaller AGs, that
> could become an issue if it gets grown to a very large size.  IOWs
> the growfs concern is mostly about the resulting AG size & AG count.
> 

You're right, I've looked through the source code and no option ever
gets passed to mkfs.xfs nor xfs_growfs related to FS size. That means
that it creates the FS with the default 4 AGs for a start.

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Re: [somewhat OT] I just discovered that Stratis uses XFS.

[Dave Chinner]

On Tue, Oct 02, 2018 at 04:25:30PM +0200, Emmanuel Florac wrote:
> Hi all, 
> in fact I just discovered that Stratis exists :)
> (https://stratis-storage.github.io/relnotes/relnotes-1.0.html) ( details
> on https://lwn.net/Articles/755454/)
> 
> Reading the FAQ (https://stratis-storage.github.io/FAQ.html) I see that
> it uses XFS as a filesystem layer. Furthermore it seems to come from
> RedHat. What are the relations with the future XFS capabilities that
> Dave (IIRC) demonstrated recently?

No relationship at all - the XFS snapshot/subvolume stuff was
already being prototyped when I first heard about Stratis.  Stratis
will be able to use this future XFS functionality however they see
fit for their users.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

Re: [somewhat OT] I just discovered that Stratis uses XFS.

[Chris Murphy]

On Tue, Oct 2, 2018 at 10:30 AM, Emmanuel Florac <eflorac@intellique.com> wrote:
> Le Tue, 2 Oct 2018 10:05:42 -0500
> Eric Sandeen <sandeen@sandeen.net> écrivait:
>
>> But if Stratis starts at 1TB it's not terrible; I'd need to look and
>> see how many AGs get created (probably 4?) and if so, 250G AGs are
>> not /too/ granular. If it's creating a lot more smaller AGs, that
>> could become an issue if it gets grown to a very large size.  IOWs
>> the growfs concern is mostly about the resulting AG size & AG count.
>>
>
> You're right, I've looked through the source code and no option ever
> gets passed to mkfs.xfs nor xfs_growfs related to FS size. That means
> that it creates the FS with the default 4 AGs for a start.

Stratis volumes are always built on dm-thin so I'd expect default
mkfs.xfs to create ~33 AG's, which is what I get when running mkfs.xfs
on LVM thin volumes.

-- 
Chris Murphy

Re: [somewhat OT] I just discovered that Stratis uses XFS.

[Emmanuel Florac]

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Le Wed, 3 Oct 2018 16:47:05 -0600
Chris Murphy <lists@colorremedies.com> écrivait:

> >
> > You're right, I've looked through the source code and no option ever
> > gets passed to mkfs.xfs nor xfs_growfs related to FS size. That
> > means that it creates the FS with the default 4 AGs for a start.  
> 
> Stratis volumes are always built on dm-thin so I'd expect default
> mkfs.xfs to create ~33 AG's, which is what I get when running mkfs.xfs
> on LVM thin volumes.
> 

Ah yes, interesting. I've created a 1TB thin volume and mkfs.xfs makes
32 AGs indeed.

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