LVM-Cache on fresh Ubuntu server install
Stephen Partington
cryptworks at gmail.com
Fri Jul 8 12:10:29 MST 2016
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
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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
>
>
--
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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