I am getting a new laptop from dell that will dual boot windows (in
case I need dell maintenance) and gentoo (real work). I have done
this often, but there are three new aspects this time.

1. ssd.
2. new udev (/usr part of boot partition?)
3. grub2.

My plan 1s to have / + /usr one partition and boot from it. All else
(/tmp, /var, /home, /opt) would be lvm2. dracut would not be used.

The laptop will have a 256GB ssd. Can I partition it the same as I
would have for an hd? Are there extra alignment considerations?

The gentoo-wiki page for grub2 mentions an "official article" for
grub2 (dev.gentoo.org/~scarabeus/grub-2-guide.xml) that
describes both mbr- and efi-based systems. Using efi and gpt have
advantages but the configuration described involves an efi partition
/boot having a FAT format. I was hoping to avoid dracut and have all
of / + /usr on the boot partition. Does this mean I should use the
mbr-based installation?

Any other tips or sources to read?

Thanks in advance,
allan

On Fri, 10 Aug 2012 10:25:51 -0400
Allan Gottlieb <gottlieb@nyu.edu> wrote:

> I am getting a new laptop from dell that will dual boot windows (in
> case I need dell maintenance) and gentoo (real work). I have done
> this often, but there are three new aspects this time.
>
> 1. ssd.
> 2. new udev (/usr part of boot partition?)
> 3. grub2.

I have one of those. But I decided to stick with traditional DOS
partitioning style and grub instead of GPT and grub2.

> My plan 1s to have / + /usr one partition and boot from it. All else
> (/tmp, /var, /home, /opt) would be lvm2. dracut would not be used.

That's OK. Lately I put /usr on / anyway, I figure 1980 was 32 years
ago and I don't *actually* need ultra-minimal rescue systems anymore. I
keep /opt on / too for the same reasons, and that the stuff I use
in /opt never changes.

>
> The laptop will have a 256GB ssd. Can I partition it the same as I
> would have for an hd? Are there extra alignment considerations?

I don't know of any special partition considerations. Just start at
the 1M mark and align on 4096 like you would for spinning disks.

What you will need is TRIM support and for that you use ext4. Just add
"discard" to the mount options for the ext4 volumes.

You also don't need an IO scheduler - ssd access is random like
RAM, no heads moving in and out so no sector ordering to worry about.
Configure the scheduler as NOOP in kernel config if all drives are ssd's



> The gentoo-wiki page for grub2 mentions an "official article" for
> grub2 (dev.gentoo.org/~scarabeus/grub-2-guide.xml) that
> describes both mbr- and efi-based systems. Using efi and gpt have
> advantages but the configuration described involves an efi partition
> /boot having a FAT format. I was hoping to avoid dracut and have all
> of / + /usr on the boot partition. Does this mean I should use the
> mbr-based installation?

Unless I'm mistaken, Windows still does not boot from GPT disks (maybe
8 is different). If that is indeed the case, then you do need to stik
with mbr for now.

Check what Google finds about your chosen Windows version's boot needs.
That will tell you what you need to od.


--
Alan McKinnon
alan.mckinnon@gmail.com

On Fri, Aug 10, 2012 at 2:22 PM, Alan McKinnon <alan.mckinnon@gmail.com> wrote:
> You also don't need an IO scheduler - ssd access is random like
> RAM, no heads moving in and out so no sector ordering to worry about.
> Configure the scheduler as NOOP in kernel config if all drives are ssd's

I've read some contradictory reports about the best scheduler for SSD.
Apparently some SSD controllers are tuned for sequential reads/writes
(drives that lean heavily on compression, I would imagine?) and for
those drives cfq or deadline may be the better choice. I would try
them all and use whatever works best for your workload.

On Fri, Aug 10 2012, Alan McKinnon wrote:

> On Fri, 10 Aug 2012 10:25:51 -0400
> Allan Gottlieb <gottlieb@nyu.edu> wrote:
>
>> I am getting a new laptop from dell that will dual boot windows (in
>> case I need dell maintenance) and gentoo (real work). I have done
>> this often, but there are three new aspects this time.
>>
>> 1. ssd.
>> 2. new udev (/usr part of boot partition?)
>> 3. grub2.
>
> I have one of those. But I decided to stick with traditional DOS
> partitioning style and grub instead of GPT and grub2.

I am leaning toward traditional partitioning, but with grub2. Do those
two not mix well?

>> The laptop will have a 256GB ssd. Can I partition it the same as I
>> would have for an hd? Are there extra alignment considerations?
>
> I don't know of any special partition considerations. Just start at
> the 1M mark and align on 4096 like you would for spinning disks.

Dell normally has a special partition of size > 40MB starting at sector
63. Presumably I ignore that one. I would then align the
used-only-for-dell-diagnostics windows partition and all linux
partitions at multiples of 4096

> What you will need is TRIM support and for that you use ext4. Just add
> "discard" to the mount options for the ext4 volumes.

Ah so I will now be using ext4. The mount man page says trim is off by
default waiting for more testing. But I will try it.

> You also don't need an IO scheduler - ssd access is random like
> RAM, no heads moving in and out so no sector ordering to worry about.
> Configure the scheduler as NOOP in kernel config if all drives are ssd's

I believe dell with be "throwing in" a removable spinning disk that can
be user swapped with the dvd so I should probably keep the I/O
scheduler.

thanks for the help,
allan

On Fri, Aug 10 2012, Paul Hartman wrote:

> On Fri, Aug 10, 2012 at 2:22 PM, Alan McKinnon <alan.mckinnon@gmail.com> wrote:
>> You also don't need an IO scheduler - ssd access is random like
>> RAM, no heads moving in and out so no sector ordering to worry about.
>> Configure the scheduler as NOOP in kernel config if all drives are ssd's
>
> I've read some contradictory reports about the best scheduler for SSD.
> Apparently some SSD controllers are tuned for sequential reads/writes
> (drives that lean heavily on compression, I would imagine?) and for
> those drives cfq or deadline may be the better choice. I would try
> them all and use whatever works best for your workload.

I see. Thanks.
allan

On Sun, 12 Aug 2012 14:11:37 -0400
Allan Gottlieb <gottlieb@nyu.edu> wrote:

> On Fri, Aug 10 2012, Alan McKinnon wrote:
>
> > On Fri, 10 Aug 2012 10:25:51 -0400
> > Allan Gottlieb <gottlieb@nyu.edu> wrote:
> >
> >> I am getting a new laptop from dell that will dual boot windows (in
> >> case I need dell maintenance) and gentoo (real work). I have done
> >> this often, but there are three new aspects this time.
> >>
> >> 1. ssd.
> >> 2. new udev (/usr part of boot partition?)
> >> 3. grub2.
> >
> > I have one of those. But I decided to stick with traditional DOS
> > partitioning style and grub instead of GPT and grub2.
>
> I am leaning toward traditional partitioning, but with grub2. Do
> those two not mix well?

I've never really used grub2 myself (can't see the point until I have
no other option than GPT and EFI), but AFAIK MBR and grub2 isn't a
problem. It might not be default, but it isn't a problem


>
> >> The laptop will have a 256GB ssd. Can I partition it the same as I
> >> would have for an hd? Are there extra alignment considerations?
> >
> > I don't know of any special partition considerations. Just start at
> > the 1M mark and align on 4096 like you would for spinning disks.
>
> Dell normally has a special partition of size > 40MB starting at
> sector 63. Presumably I ignore that one. I would then align the
> used-only-for-dell-diagnostics windows partition and all linux
> partitions at multiples of 4096

Correct

>
> > What you will need is TRIM support and for that you use ext4. Just
> > add "discard" to the mount options for the ext4 volumes.
>
> Ah so I will now be using ext4. The mount man page says trim is off
> by default waiting for more testing. But I will try it.

I think that man page is badly out of date (unless the ext4 devs
understand "testing" to mean something very different to what you and I
understand)

>
> > You also don't need an IO scheduler - ssd access is random like
> > RAM, no heads moving in and out so no sector ordering to worry
> > about. Configure the scheduler as NOOP in kernel config if all
> > drives are ssd's
>
> I believe dell with be "throwing in" a removable spinning disk that
> can be user swapped with the dvd so I should probably keep the I/O
> scheduler.

You can set the scheduler per-device too, more info here:

https://wiki.archlinux.org/index.php/Solid_State_Drives#I.2FO_Scheduler

Someone else reported though that Deadline scheduler can actually
performs better, I also read that somewhere. Maybe you should do some
initial tests yourself before deciding


--
Alan McKinnon
alan.mckinnon@gmail.com

On Sun, 12 Aug 2012 14:11:37 -0400, Allan Gottlieb wrote:

> > I have one of those. But I decided to stick with traditional DOS
> > partitioning style and grub instead of GPT and grub2.
>
> I am leaning toward traditional partitioning, but with grub2. Do those
> two not mix well?

GRUB2 works fine with MBR partition tables. But if you're starting from
scratch, you may as well use GPT and get rid of the legacy MBR
limitations and fragility.


--
Neil Bothwick

Procedure: (n.) a method of performing a program sub-task in an
inefficient way by extensively using the stack instead of a GOTO.

On Mon, Aug 13, 2012 at 4:06 AM, Neil Bothwick <neil@digimed.co.uk> wrote:

On Sun, 12 Aug 2012 14:11:37 -0400, Allan Gottlieb wrote:



> > I have one of those. But I decided to stick with traditional DOS

> > partitioning style and grub instead of GPT and grub2.

>

> I am leaning toward traditional partitioning, but with grub2. *Do those

> two not mix well?



GRUB2 works fine with MBR partition tables. But if you're starting from

scratch, you may as well use GPT and get rid of the legacy MBR

limitations and fragility.

I'm not dissing GPT...but what's fragile about MBR?
--
:wq

On Mon, Aug 13 2012, Neil Bothwick wrote:

> On Sun, 12 Aug 2012 14:11:37 -0400, Allan Gottlieb wrote:
>
> GRUB2 works fine with MBR partition tables. But if you're starting from
> scratch, you may as well use GPT and get rid of the legacy MBR
> limitations and fragility.

OK, but what about EFI? That seems to involve more work and the writeup
suggests that you need a separate (FAT32) boot partition?

allan

On Sun, Aug 12 2012, Alan McKinnon wrote:

> On Sun, 12 Aug 2012 14:11:37 -0400
> Allan Gottlieb <gottlieb@nyu.edu> wrote:
>
>> On Fri, Aug 10 2012, Alan McKinnon wrote:
>>
>> > You also don't need an IO scheduler - ssd access is random like
>> > RAM, no heads moving in and out so no sector ordering to worry
>> > about. Configure the scheduler as NOOP in kernel config if all
>> > drives are ssd's
>>
>> I believe dell with be "throwing in" a removable spinning disk that
>> can be user swapped with the dvd so I should probably keep the I/O
>> scheduler.
>
> You can set the scheduler per-device too, more info here:
>
> https://wiki.archlinux.org/index.php/Solid_State_Drives#I.2FO_Scheduler
>
> Someone else reported though that Deadline scheduler can actually
> performs better, I also read that somewhere. Maybe you should do some
> initial tests yourself before deciding

Yes, that sounds like a good idea and the article you just mentioned
looks to be quite helpful.

thanks,
allan