LVM-Cache on fresh Ubuntu server install
Stephen Partington
cryptworks at gmail.com
Fri Jul 8 11:57:13 MST 2016
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
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>>> http://lists.phxlinux.org/mailman/listinfo/plug-discuss
>>>
>>
>>
>>
>> --
>> 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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