[Thincrust-devel] [Overview] appliance-tools patches on LVM support

[Joey Boggs]

On 01/30/2012 04:15 AM, Marek Goldmann wrote:
> Hi all,
>
> First of all - thanks for the patch! It would be very nice to expose 
> kickstart's LVM support.
>
> Now the hard part - sadly I am not the right guy to review that patch. 
> Would anyone be willing to review it instead of me?
>
> --Marek
>
> On 01/12/2012 06:44 AM, henry_huang at trendmicro.com.cn wrote:
>> Hi, Marek
>>
>> Days ago, my colleague (Yongjun) has sent the four patches on help 
>> appliance-tools support LVM.
>> As you requested, I will add more description on these patches here.
>>
>> [Background]
>> The Appliance Creation Tool is a nice tool to create Appliance Images 
>> from a redhat-series kickstart file. This tool uses the liveCD 
>> creator API as well as patches to the LIVECD API to create a 
>> multi-partitioned disk image, contained in the applianace-tools package.
>> These disk images can then be booted in a virtual container such as 
>> Xen, KVM, and VMware. Currently, BoxGrinder (BG) based on the 
>> appliance-tools is a popular project to grind out appliances for 
>> multiple virtualization and Cloud providers, like Amazon EC2.
>> Actually we (TrendMicro) have many projects working on these fields, 
>> and we'd like to share what we have now in these fields, like LVM 
>> support in appliance-tools here.
>>
>> [Problem]
>> However, as we know, there is no current support on logical volume 
>> management (LVM) in appliance-tools. LVM has long been a valuable 
>> technique on managing disk drives and similar mass-storage devices.
>> We can get much benefit from LVM:
>> 1. Managing large hard disk farms by letting you add disks, replace 
>> disks, copy and share contents from one disk to another without 
>> disrupting service (hot swapping).
>> 2. Making backups by taking "snapshots."
>> 3. Creating single logical volumes of multiple physical volumes or 
>> entire hard disks, allowing for dynamic volume resizing.
>> Therefore, our patches are working on this problem, to make 
>> appliance-tools support LVM.
>>
>> [Solution]
>> We have provided four patches on this problem.
>> [PATCH 1/4] Add LVM physical volume partition type support
>> [PATCH 2/4] Add Logical Volume Management(LVM) group interface to 
>> partitionedfs
>> [PATCH 3/4] Add Logical Volume interface to partitionedfs
>> [PATCH 4/4] Add Logical Volume Management to ApplianceImageCreator
>>
>> 1. Overview on appliance-tools components.
>> Appliance-tools is mainly based on "imgcreate" library in LiveCD tools.
>> Appliance-tools: __init__.py + appliance.py + partitionedfs.py
>> * __init__.py:         =>  appcreate, support for creating appliance 
>> images
>> * appliance.py:     Appliance Image Creator class
>> * partitionedfs.py:     partitioned files system class, extends fs.py 
>> from imgcreate/fs.py
>>
>> 2. Key problems in partitionedfs.py components.
>> a) imgcreate/kickstart.py does not support LVM configuration on 
>> kickstart files.
>> b) imgcreate/fs.py does not support LVM interfaces
>>
>> For the first problem:
>> However, patches on imgcreate/kickstart.py to support LVM 
>> configuration are much more difficult and it also will affect 
>> upstream live-tools.
>> As "pykickstart" library (already used in appliance-tools) has 
>> appropriate LVM options, we decide to reuse it.
>> @@ -120,6 +128,8 @@ class ApplianceImageCreator(ImageCreator):
>>
>>     #list of partitions from kickstart file
>>     parts = kickstart.get_partitions(self.ks)
>> +    groups = self.ks.handler.volgroup.vgList
>> +    volumes = self.ks.handler.logvol.lvList
>>
>>     #list of disks where a disk is an dict with name: and size
>>     disks = []
>> More information can be found in [PATCH 4/4].
>>
>> For the second problem:
>> We have to add a new interface on LVM support at "partitionedfs.py".
>> Here are three important functions added to support LVM in 
>> "partitionedfs.py".
>> self.__format_volumes()
>> self.__map_volumes()
>> self.__unmap_volumes()
>> More information can be found in [PATCH 1/4], [PATCH 2/4], [PATCH 3/4]
>>
>> [TODO]
>> 1. Our patches currently do not support for grub2.
>> 2. We will support to calculate LVM size to fit the size of pv.<id>, 
>> as --grow support for "logvol" options.
>>
>> If you have any comments, please let me know.
>> Thanks&  Best wishes,
>>
>> Henry Huang | QA Engineer, CDC Enterprise Segment
>> Building B, Soho International Plaza, No.48
>> Ning Nan Avenue, Nanjing 210012, P. R. China
>> Office: 86-25-52386680
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>
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I'll try and get to it this afternoon EST, if not tomorrow