[Pacemaker] Issue with ordering

[Florian Haas]

On Thu, Mar 29, 2012 at 11:40 AM, Vladislav Bogdanov
<bubble at hoster-ok.com> wrote:
> Hi Florian,
>
> 29.03.2012 11:54, Florian Haas wrote:
>> On Thu, Mar 29, 2012 at 10:07 AM, Vladislav Bogdanov
>> <bubble at hoster-ok.com> wrote:
>>> Hi Andrew, all,
>>>
>>> I'm continuing experiments with lustre on stacked drbd, and see
>>> following problem:
>>
>> At the risk of going off topic, can you explain *why* you want to do
>> this? If you need a distributed, replicated filesystem with
>> asynchronous replication capability (the latter presumably for DR),
>> why not use a Distributed-Replicated GlusterFS volume with
>> geo-replication?
>
> I need fast POSIX fs scalable to tens of petabytes with support for
> fallocate() and friends to prevent fragmentation.
>
> I generally agree with Linus about FUSE and userspace filesystems in
> general, so that is not an option.

I generally agree with Linus and just about everyone else that
filesystems shouldn't require invasive core kernel patches. But I
digress. :)

> Using any API except what VFS provides via syscalls+glibc is not an
> option too because I need access to files from various scripted
> languages including shell and directly from a web server written in C.
> Having bindings for them all is a real overkill. And it all is in
> userspace again.
>
> So I generally have choice of CEPH, Lustre, GPFS and PVFS.
>
> CEPH is still very alpha, so I can't rely on it, although I keep my eye
> on it.
>
> GPFS is not an option because it is not free and produced by IBM (can't
> say which of these two is more important ;) )
>
> Can't remember why exactly PVFS is a no-go, their site is down right
> now. Probably userspace server implementation (although some examples
> like nfs server discredit idea of in-kernel servers, I still believe
> this is a way to go).

Ceph is 100% userspace server side, jftr. :) And it has no async
replication capability at this point, which you seem to be after.

> Lustre is widely deployed, predictable and stable. It fully runs in
> kernel space. Although Oracle did its best to bury Lustre development,
> it is actively developed by whamcloud and company. They have builds for
> EL6, so I'm pretty happy with this. Lustre doesn't have any replication
> built-in so I need to add it on a lower layer (no rsync, no rsync, no
> rsync ;) ). DRBD suits my needs for a simple HA.
>
> But I also need datacenter-level HA, that's why I evaluate stacked DRBD
> and tickets with booth.
>
> So, frankly speaking, I decided to go with Lustre not because it is so
> cool (it has many-many niceties), but because all others I know do not
> suit my needs at all due to various reasons.
>
> Hope this clarifies my point,

It does. Doesn't necessarily mean I agree, but the point you're making is fine.

Cheers,
Florian

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