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

[Marek Goldmann]

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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