[linux-lvm] Question on mixing technologies

[linux-lvm] Question on mixing technologies

[Georges Giralt]

Hello guys,

I've an Ubuntu machine with two SATA mechanical drives on software raid 1.

This md is the sole PV of the LVM installation.

As the mainboard has been changed recently, it has an M.2 plug. And I'm 
been offered a 128 GB M.2 NGFF card.

So far so good.

Question : Will I gain something adding the M.2 card as a second PV on 
my LVM setup and moving the system LV to it ?

What are your experience on the subject ?

Many thanks in advance for your advice !


-- 
"If a man empties his purse into his head, no man can take it away from him.
An investment in knowledge always pays the best interest"


Benjamin Franklin.

Re: [linux-lvm] Question on mixing technologies

[Gionatan Danti]

You basically have two possibilities:

1) move the root fs on the M.2 disk, which will give you much higher 
system responsiveness compared to the mechanical disks; however, any 
data/application installed on the HDD will be slow as always;

2) configure lvmcache [1] for using the M.2 disk as a read-only 
(writethrough) caching device for the mechanical disks, which will give 
you somewhat lesser system responsiveness but *any* cache-friendly 
application will be accelerated from the M.2 disk.

[1] http://man7.org/linux/man-pages/man7/lvmcache.7.html

Regards.

Il 12-05-2017 18:21 Georges Giralt ha scritto:
> Hello guys,
> 
> I've an Ubuntu machine with two SATA mechanical drives on software raid 
> 1.
> 
> This md is the sole PV of the LVM installation.
> 
> As the mainboard has been changed recently, it has an M.2 plug. And
> I'm been offered a 128 GB M.2 NGFF card.
> 
> So far so good.
> 
> Question : Will I gain something adding the M.2 card as a second PV on
> my LVM setup and moving the system LV to it ?
> 
> What are your experience on the subject ?
> 
> Many thanks in advance for your advice !

-- 
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8

Re: [linux-lvm] Question on mixing technologies

[Georges Giralt]

Thank you, Gionatan for your answer.

I finally had time to test the first solution, having the root FS on the 
M.2 card and everything else (including /var and /tmp) on the mechanical 
drives.

The responsiveness of the machine is awesome and, for now, without any 
glitch or problem. So I may retain this solution.

The only remaining question is how to trim the device as it is not 
"mounted". Is there a special pvcreate or LVM option to have this device 
trimmed when it should be ?

Have a nicce day !


Le 13/05/2017 � 14:16, Gionatan Danti a �crit :
> You basically have two possibilities:
>
> 1) move the root fs on the M.2 disk, which will give you much higher 
> system responsiveness compared to the mechanical disks; however, any 
> data/application installed on the HDD will be slow as always;
>
> 2) configure lvmcache [1] for using the M.2 disk as a read-only 
> (writethrough) caching device for the mechanical disks, which will 
> give you somewhat lesser system responsiveness but *any* 
> cache-friendly application will be accelerated from the M.2 disk.
>
> [1] http://man7.org/linux/man-pages/man7/lvmcache.7.html
>
> Regards.
>
> Il 12-05-2017 18:21 Georges Giralt ha scritto:
>> Hello guys,
>>
>> I've an Ubuntu machine with two SATA mechanical drives on software 
>> raid 1.
>>
>> This md is the sole PV of the LVM installation.
>>
>> As the mainboard has been changed recently, it has an M.2 plug. And
>> I'm been offered a 128 GB M.2 NGFF card.
>>
>> So far so good.
>>
>> Question : Will I gain something adding the M.2 card as a second PV on
>> my LVM setup and moving the system LV to it ?
>>
>> What are your experience on the subject ?
>>
>> Many thanks in advance for your advice !
>

-- 
"If a man empties his purse into his head, no man can take it away from him.
An investment in knowledge always pays the best interest"


Benjamin Franklin.

Re: [linux-lvm] Question on mixing technologies

[Xen]

Georges Giralt schreef op 31-05-2017 8:53:

> The only remaining question is how to trim the device as it is not
> "mounted". Is there a special pvcreate or LVM option to have this
> device trimmed when it should be ?

It is definitely mounted if your root is on it.

Regards.

Re: [linux-lvm] Question on mixing technologies

[Stuart Gathman]

On 05/31/2017 02:53 AM, Georges Giralt wrote:
> I finally had time to test the first solution, having the root FS on
> the M.2 card and everything else (including /var and /tmp) on the
> mechanical drives.
>
> The responsiveness of the machine is awesome and, for now, without any
> glitch or problem. So I may retain this solution.
>
> The only remaining question is how to trim the device as it is not
> "mounted". Is there a special pvcreate or LVM option to have this
> device trimmed when it should be ?
# fstrim /

Re: [linux-lvm] Question on mixing technologies

[Georges Giralt]

Hello !

Here I'm again.

I've played a bit more with my setup.

I've changed two computers : a server having got a new mainboard with an 
M.2 plug, In it I installed a NVME SSD card.

On this machine, I created a PV onto this device and added this PV to 
the VG holding the system. I then did pvmove to place the lv containing 
/ and /usr to the SSD. Perfect !

The server is really highly responsive and, as the /var and /tmp are 
still on mechanical drives I hope the SSD will be long lived.

On my laptop, the SSD has been used for the / and /usr outside of LVM 
(the laptop had already a GPT disk and I decided not to use LVM at all).

I can't compare the behavior because of the huge difference between the 
two machines, but I'm really happy with both settings.

Thnks for your help.


Le 01/06/2017 � 02:31, Stuart Gathman a �crit�:
> On 05/31/2017 02:53 AM, Georges Giralt wrote:
>> I finally had time to test the first solution, having the root FS on
>> the M.2 card and everything else (including /var and /tmp) on the
>> mechanical drives.
>>
>> The responsiveness of the machine is awesome and, for now, without any
>> glitch or problem. So I may retain this solution.
>>
>> The only remaining question is how to trim the device as it is not
>> "mounted". Is there a special pvcreate or LVM option to have this
>> device trimmed when it should be ?
> # fstrim /
>
> _______________________________________________
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> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>

-- 
"If a man empties his purse into his head, no man can take it away from him.
An investment in knowledge always pays the best interest"


Benjamin Franklin.