LVM-Cache on fresh Ubuntu server install

Stephen Partington cryptworks at gmail.com
Fri Jul 8 13:02:53 MST 2016 

And success. Server is now up with LVMcache and boots nicely. Very
educational!

And there is a noticeable boost to performance.

And a touch of a blogpost about it.
http://cryptworkslinux.blogspot.com/2016/07/ubuntu-1604-home-server-and-lvm-cache.html

On Fri, Jul 8, 2016 at 12:10 PM, Stephen Partington <cryptworks at gmail.com>
wrote:

> additional http://scyu.logdown.com/posts/519001-ubuntu-lvmcache-setup for
> anyone else that is interested where this thread goes.
>
> On Fri, Jul 8, 2016 at 11:57 AM, Stephen Partington <cryptworks at gmail.com>
> wrote:
>
>> And i spoke too soon...
>>
>>
>> http://unix.stackexchange.com/questions/173704/booting-from-an-lvm-cached-volume
>>
>> so now to get to a point where i can rebuild this or just reinstall from
>> scratch... i think the latter might be easier.
>>
>> On Fri, Jul 8, 2016 at 11:41 AM, Stephen Partington <cryptworks at gmail.com
>> > wrote:
>>
>>> wow, that was much smoother than i thought it would be.
>>>
>>> I guess setting things up the way i have ahead of time was a good thing.
>>> now to move on to the rest of life. (also an interesting idea to set up a
>>> desktop/laptop this way to see how life works)
>>>
>>> lvm> vgs
>>>   VG     #PV #LV #SN Attr   VSize VFree
>>>   System   2   1   0 wz--n- 1.02t 1.38g
>>> lvm> pvs
>>>   PV         VG     Fmt  Attr PSize   PFree
>>>   /dev/sda3  System lvm2 a--  117.38g 1.38g
>>>   /dev/sdb2  System lvm2 a--  922.20g    0
>>> lvm> lvs
>>>   LV     VG     Attr       LSize   Pool    Origin         Data%  Meta%
>>>  Move Log Cpy%Sync Convert
>>>   System System Cwi-aoC--- 922.20g [cache] [System_corig] 0.00   0.70
>>>          0.00
>>>
>>>
>>> On Fri, Jul 8, 2016 at 11:24 AM, Stephen Partington <
>>> cryptworks at gmail.com> wrote:
>>>
>>>> ​The biggest issue i have is that i am working with a mac mini. the 1T
>>>> drive is a 5400 rpm drive. this has been my home server for a while running
>>>> server 2016, but it is time to put something more useful on it.
>>>>
>>>> Part of this is specifically to learn how to use lvm and lvmcache.​ And
>>>> ram is on the list for this server just not in the budget yet.
>>>>
>>>> I am not worried about catastrophic failure or the like as nothing
>>>> lives on this server that does not already live anywhere else.
>>>>
>>>> I did the install with the Ubuntu server install so i could at least
>>>> get lvm set up partly ahead of time. so it looks like I am in a good place.
>>>> I was reading that article as i received your email.
>>>>
>>>> So now to extend the vg create the cache and meta lv's and turn things
>>>> on.
>>>>
>>>> lvm> pvscan
>>>>   PV /dev/sdb2   VG System          lvm2 [922.20 GiB / 0    free]
>>>>   PV /dev/sda3                      lvm2 [117.38 GiB]
>>>>   Total: 2 [1.02 TiB] / in use: 1 [922.20 GiB] / in no VG: 1 [117.38
>>>> GiB]
>>>> lvm> pvs
>>>>   PV         VG     Fmt  Attr PSize   PFree
>>>>   /dev/sda3         lvm2 ---  117.38g 117.38g
>>>>   /dev/sdb2  System lvm2 a--  922.20g      0
>>>> lvm> vgs
>>>>   VG     #PV #LV #SN Attr   VSize   VFree
>>>>   System   1   1   0 wz--n- 922.20g    0
>>>> lvm> vgdisplay
>>>>   --- Volume group ---
>>>>   VG Name               System
>>>>   System ID
>>>>   Format                lvm2
>>>>   Metadata Areas        1
>>>>   Metadata Sequence No  2
>>>>   VG Access             read/write
>>>>   VG Status             resizable
>>>>   MAX LV                0
>>>>   Cur LV                1
>>>>   Open LV               1
>>>>   Max PV                0
>>>>   Cur PV                1
>>>>   Act PV                1
>>>>   VG Size               922.20 GiB
>>>>   PE Size               4.00 MiB
>>>>   Total PE              236082
>>>>   Alloc PE / Size       236082 / 922.20 GiB
>>>>   Free  PE / Size       0 / 0
>>>>
>>>>
>>>> On Fri, Jul 8, 2016 at 11:02 AM, Matt Graham <mhgraham at crow202.org>
>>>> wrote:
>>>>
>>>>> On 2016-07-08 10:00, Stephen Partington wrote:
>>>>>
>>>>>> 1T spinning disk and 128G SSD installed. [...] going with LVM-Cache
>>>>>> Sadly the Ubuntu server installation does not have the option of
>>>>>> setting up LVM for anything other than its most basic configuration
>>>>>>
>>>>>
>>>>> LVM is complicated, and using LVM-cache is a bit more complicated than
>>>>> just making some PVs and putting them into a VG and then making LVs.
>>>>>
>>>>> What I understand about LVM is that you can build your LVM group and
>>>>>> then migrate/expand it without a full install/wipe or 3rd disk device
>>>>>> to host your core os installation. Can this be done for LVM cache as
>>>>>> well?
>>>>>>
>>>>>
>>>>> Yes.  Your setup would be something like this:  2 PVs, one on the fast
>>>>> disk, one on the slow disk[0].  One VG with both PVs in it.  Multiple LVs.
>>>>> One named root on the fast disk (mounted at / obviously), one small one
>>>>> named cache-meta on the fast disk, one larger one named cache on the fast
>>>>> disk, and finally one larger one named origin on the slow disk.  You'd
>>>>> probably mount the last one on /data or /home or wherever makes sense to
>>>>> put the large amount of stuff you want to serve up.  I suppose you could
>>>>> put / on the spinny-disk and use almost all of the SSD for cache too.  Your
>>>>> call.
>>>>>
>>>>> If you already have some PVs and LVs set up, you might need to use
>>>>> pvmove and lvresize and resize2fs to resize filesystems and LVs and move
>>>>> them to the appropriate PV.  These things are of course doable from a
>>>>> running system and should not cause any problems.
>>>>>
>>>>> https://rwmj.wordpress.com/2014/05/22/using-lvms-new-cache-feature/
>>>>> describes all the commands you'd need to run to make this stuff happen.
>>>>> And getting an additional 4G or 8G of RAM might help more than using an SSD
>>>>> as a cache, depending on what exactly is going on.
>>>>>
>>>>> (I haven't actually tried this, but I've got a 32G unused partition on
>>>>> my SSD right now, and this could be a fun weekend project.  I will let you
>>>>> know if I run into any problems.)
>>>>>
>>>>> [0] With 1T disks as cheap as they are, consider a softRAID-1 instead
>>>>> of a single spinny disk.  Disk failures are No Fun At All.
>>>>>
>>>>> --
>>>>> Crow202 Blog: http://crow202.org/wordpress
>>>>> There is no Darkness in Eternity
>>>>> But only Light too dim for us to see.
>>>>> ---------------------------------------------------
>>>>> PLUG-discuss mailing list - PLUG-discuss at lists.phxlinux.org
>>>>> To subscribe, unsubscribe, or to change your mail settings:
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>>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> A mouse trap, placed on top of your alarm clock, will prevent you from
>>>> rolling over and going back to sleep after you hit the snooze button.
>>>>
>>>> Stephen
>>>>
>>>>
>>>
>>>
>>> --
>>> A mouse trap, placed on top of your alarm clock, will prevent you from
>>> rolling over and going back to sleep after you hit the snooze button.
>>>
>>> Stephen
>>>
>>>
>>
>>
>> --
>> A mouse trap, placed on top of your alarm clock, will prevent you from
>> rolling over and going back to sleep after you hit the snooze button.
>>
>> Stephen
>>
>>
>
>
> --
> A mouse trap, placed on top of your alarm clock, will prevent you from
> rolling over and going back to sleep after you hit the snooze button.
>
> Stephen
>
>


-- 
A mouse trap, placed on top of your alarm clock, will prevent you from
rolling over and going back to sleep after you hit the snooze button.

Stephen
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