SSD Partitioning OP/Trim recommendations

[Richard Shaw]

On Wed, Dec 18, 2013 at 9:38 AM, Robert Moskowitz <rgm at htt-consult.com>wrote:

>
> On 12/18/2013 10:15 AM, Mihamina RKTMB wrote:
>
>> On 12/18/2013 04:38 PM, Robert Moskowitz wrote:
>>
>>> Also discourages using LVM.  I have often wondered why I use LVM on my
>>> notebooks; I don't see the gain over just plain EXT4 partitions.  I have
>>> read a number of articles and I can't find any solid advantage.
>>>
>>
>> Well, I dont have a notebook, but a laptop (16GB RAM, Corei7-8 threads,
>> 512 SSD Samsung 840 Pro)
>> I use it for work, and I heavily virtualize on it.
>> I have 1LV per VM. VMs are "small" (2GB RAM, 5GB disk space), but they
>> are numerous (mostly 4-5 VMs turned on)
>> When I clone a VM, the LV gets cloned too.
>> I find it very usefull and clean on the drive.
>>
>
> OK.  Excellent justification for LVM.  So far I have not done VMs, but I
> have been thinking heavily about it.  But not HOW to do it. Seems like I
> probably should if I want to set up my drive now for VMs soon.
>
> And well, my main system is a laptop, though only 12".  Just the right
> size to use in flight.
>
>
If you're a typical desktop user (unlike the situation above) and you're
not going to reserve any space on your drive, I don't think there's a
compelling reason to use LVM. I do anyway since that's what anaconda
defaults to...

To explain what I mean... Unless you're going to create multiple LV
(perhaps one for "/", one for "/var", one for "/home") and reserve some
space on your disk in case you guessed wrong so you can add more space to
any of those, then what's the point?

This makes even less sense for a laptop, but lets look at a desktop
situation. Sure you could add a second disk, add it to your volume group,
add space to your LV, and resize your filesystem to use it. One problem
though, you've created another point of failure for your FS (two disks)
without getting anything in exchange. It's not striped (you can do LV
striping, but that's another discussion altogether), it's not mirrored,
there's no parity. So why do it?

In a server/enterprise setting I think it makes a lot more sense where
you're likely to need to use LVM to span across multiple raid arrays, SANs,
etc.

Just my $.02..

Richard
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