[Users] simfs challenge

[Konstantin Khorenko]

Hi Nick,

i believe it's not the question about vzpbackup, but about
ploop compact which in your case works not that efficient.

Yes, we do work on improving ploop compact and would appreciate in case
you can provide us metadata of that "bad" ploop image.

Please, file an issue at bugs.openvz.org, i'll post instructions there.
(No real user data is needed, only fs metadata, which blocks are filled which are not, etc)

Thank you.

--
Best regards,

Konstantin Khorenko,
Virtuozzo Linux Kernel Team

On 01/28/2016 02:42 PM, Nick Knutov wrote:
> Hello,
>
> One of big reasons to prefer simfs over ploop is disk space overhead in
> ploop after using snapshots (for backups for example).
> It can be really huge - we have one CT which takes 120Gb instead of 60Gb
> (df -h inside) after daily backups with vzpbackup (*) tool. It's
> after(!) ploop merge & compact.
>
> Do you plan to make some improvements for this case?
>
> (*) https://github.com/andreasfaerber/vzpbackup
>
> 28.01.2016 14:27, Konstantin Khorenko пишет:
>> Hi All,
>>
>> so, this is the current situation with simfs:
>>
>> First of all we cannot implement as it was previously (in OpenVZ 6,
>> 2.6.32-x kernels).
>> This is because there is no vzfs in Virtuozzo 7, but all quota related
>> code used by simfs
>> was shared between vzfs and simfs, and maintaining that code for simfs
>> only is definitely
>> not the thing we'd be happy to do.
>> Yes, we definitely want to reuse some mainstream (or write a
>> mainstream-able) code for it.
>>
>> So, how this could be implemented?
>>
>> "Old" simfs fs without quota - is just a bindmount => this is a start
>> point.
>> 1st level quota for simfs-based Containers (the quota for the
>> Container as a whole) can be
>> implemented using project quota which is going to be accepted to
>> mainstream sooner or later.
>>
>> As for the 2nd level quota (per-user quota inside a CT), we had not
>> found any good solution
>> during our internal discussions, so ideas from community are very
>> welcome.
>>
>> So what do we have at the moment: you can create a simfs-based
>> Container in Virtuozzo 7
>> (see instructions below), but cannot manage quota for it.
>>
>> What should be done further (that's what you can help us with):
>>
>> 1. Take project quota kernel patches (which Stas Kinsbursky alredy
>> ported to vz7 kernel
>> some time ago), apply them to current vz7 kernel - you'll get the
>> kernel able to manage
>> project quota.
>>
>> 2. Need to add project quota support to appropriate userspace tools:
>> quota-tools and e2fsprogs
>> see details at https://bugs.openvz.org/browse/OVZ-6619
>>
>> Hope that helps to understand our plans on simfs in Virtuozzo 7
>> and looking forward for a hero who could drive this forward! :)
>>
>>
>>
>> More formal feature description is below:
>>
>> ===========================================================================================
>>
>> 1. Feature
>> simfs filesystem for Virtuozzo 7 Containers
>>
>>
>> 2. Description
>> https://bugs.openvz.org/browse/OVZ-6613
>> https://jira.sw.ru/browse/PSBM-40730
>>
>> Differences between recommended Containers disk backend (ploop) and
>> simfs:
>> https://openvz.org/CT_storage_backends
>>
>> Unlike previous versions of OpenVZ, simfs layout in Virtuozzo 7 is
>> based on bindmounts.
>> This means once you start a simfs-based Container, effectively
>> "private" area of a Container is bindmounted to the "root" Container
>> area.
>> That's it.
>>
>> How to create a simfs-based Container:
>> * set VEFSTYPE=simfs in the /etc/vz/vz.conf
>> # vzctl create $VEID
>>
>> 3. Products
>> Virtuozzo 7, libvzctl-7.0.170
>>
>>
>> 4. Testing
>> just a validation:
>> - create a Container
>> - start/stop the Container
>> - destroy the Container
>>
>> 5. Known issues
>> * quota for simfs-based Containers is not implemented
>>    - 1st level quota (for the Container as a whole) is planned to be
>> implemented via project quota
>>      https://bugs.openvz.org/browse/OVZ-6619
>>
>>    - 2nd level quota (per-user quota inside a Container) is not planned
>>
>> * online migration of a simfs-based Container is not implemented
>>
>>
>> 6. Feature owner
>> Kernel part:    Stanislav Kinsbursky <skinsbursky at virtuozzo.com>
>> Userspace part: Igor Sukhih <igor at virtuozzo.com>
>>
>>
>> --
>> Best regards,
>>
>> Konstantin Khorenko,
>> Virtuozzo Linux Kernel Team
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>