[gentoo-user] new installation (ssd, new udev, grub2)

[gentoo-user] new installation (ssd, new udev, grub2)

[Allan Gottlieb]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Alan McKinnon]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Paul Hartman]

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.

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Allan Gottlieb]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Allan Gottlieb]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Alan McKinnon]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Neil Bothwick]

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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.

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Michael Mol]

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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

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Allan Gottlieb]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Allan Gottlieb]

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

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Neil Bothwick]

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On Mon, 13 Aug 2012 08:17:23 -0400, Michael Mol 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.
> >  
> 
> I'm not dissing GPT...but what's fragile about MBR?

The MBR contains only details of the primary partitions, the logical
partition details are scattered over the disk, and there's no backup of
either. Making your own backup is non-trivial, even if you bother.

GPT puts all the partition information in one block, and keeps a backup
copy elsewhere (rather like filesystems do with superblocks).

That makes GPT more resilient to corruption in the first place and easier
to recover if things do go bad. Remember that GPT was designed with the
benefit of decades of hindsight over the limitations of DOS partition
tables.


-- 
Neil Bothwick

In plumbing, a straight flush is better than a full house.

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Alan McKinnon]

On Mon, 13 Aug 2012 08:17:23 -0400
Michael Mol <mikemol@gmail.com> wrote:

> 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?

it's 30 years old,
only 4 primary partitions,
only 16 extended partitions,
it's got that weird DOS boot flag thing,
it all has to fit in one sector.

I had to fix a mispartitioned disk over the weekend, this really should
have been a simple mv-type operation, but because all 4 primary
partitions were in use I had to disable swap and use it as a leap-frog
area. It felt like I was playing 15 pieces with the disk. That's
fragile - not that the disk breaks, but that it breaks my ability to
set the thing up easily.

Basically, mbr was built to cater for the needs of DOS-3. In the
meantime, 1982 called and they want their last 30 years back.

Just because we can hack workarounds into it to get it to function
doesn't mean we should continue to use it.


-- 
Alan McKinnon
alan.mckinnon@gmail.com

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Michael Mol]

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On Mon, Aug 13, 2012 at 11:47 AM, Alan McKinnon <alan.mckinnon@gmail.com>wrote:

> On Mon, 13 Aug 2012 08:17:23 -0400
> Michael Mol <mikemol@gmail.com> wrote:
>
> > 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?
>
> it's 30 years old,
> only 4 primary partitions,
> only 16 extended partitions,
> it's got that weird DOS boot flag thing,
> it all has to fit in one sector.
>
> I had to fix a mispartitioned disk over the weekend, this really should
> have been a simple mv-type operation, but because all 4 primary
> partitions were in use I had to disable swap and use it as a leap-frog
> area. It felt like I was playing 15 pieces with the disk. That's
> fragile - not that the disk breaks, but that it breaks my ability to
> set the thing up easily.
>
> Basically, mbr was built to cater for the needs of DOS-3. In the
> meantime, 1982 called and they want their last 30 years back.
>
> Just because we can hack workarounds into it to get it to function
> doesn't mean we should continue to use it.
>

You misunderstand me. I wasn't arguing that GPT wasn't perhaps more elegant
than MBR and dos partitions. I wanted to know what was _fragile_ about MBR.
Completely different things.

-- 
:wq

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Pandu Poluan]

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On Aug 13, 2012 11:04 PM, "Michael Mol" <mikemol@gmail.com> wrote:
>
> On Mon, Aug 13, 2012 at 11:47 AM, Alan McKinnon <alan.mckinnon@gmail.com>
wrote:
>>
>> On Mon, 13 Aug 2012 08:17:23 -0400
>> Michael Mol <mikemol@gmail.com> wrote:
>>
>> > 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?
>>
>> it's 30 years old,
>> only 4 primary partitions,
>> only 16 extended partitions,
>> it's got that weird DOS boot flag thing,
>> it all has to fit in one sector.
>>
>> I had to fix a mispartitioned disk over the weekend, this really should
>> have been a simple mv-type operation, but because all 4 primary
>> partitions were in use I had to disable swap and use it as a leap-frog
>> area. It felt like I was playing 15 pieces with the disk. That's
>> fragile - not that the disk breaks, but that it breaks my ability to
>> set the thing up easily.
>>
>> Basically, mbr was built to cater for the needs of DOS-3. In the
>> meantime, 1982 called and they want their last 30 years back.
>>
>> Just because we can hack workarounds into it to get it to function
>> doesn't mean we should continue to use it.
>
>
> You misunderstand me. I wasn't arguing that GPT wasn't perhaps more
elegant than MBR and dos partitions. I wanted to know what was _fragile_
about MBR. Completely different things.
>

Well, for one, MBR has no copy, and it is not protected from corruption.

GPT has 2 copies: One at the head of the disk right behind a "legacy MBR",
and another at the end of the disk. Both copies are protected by magic
strings and CRC.

Rgds,

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Alan McKinnon]

On Mon, 13 Aug 2012 11:55:31 -0400
Michael Mol <mikemol@gmail.com> wrote:

> On Mon, Aug 13, 2012 at 11:47 AM, Alan McKinnon
> <alan.mckinnon@gmail.com>wrote:
> 
> > On Mon, 13 Aug 2012 08:17:23 -0400
> > Michael Mol <mikemol@gmail.com> wrote:
> >
> > > 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?
> >
> > it's 30 years old,
> > only 4 primary partitions,
> > only 16 extended partitions,
> > it's got that weird DOS boot flag thing,
> > it all has to fit in one sector.
> >
> > I had to fix a mispartitioned disk over the weekend, this really
> > should have been a simple mv-type operation, but because all 4
> > primary partitions were in use I had to disable swap and use it as
> > a leap-frog area. It felt like I was playing 15 pieces with the
> > disk. That's fragile - not that the disk breaks, but that it breaks
> > my ability to set the thing up easily.
> >
> > Basically, mbr was built to cater for the needs of DOS-3. In the
> > meantime, 1982 called and they want their last 30 years back.
> >
> > Just because we can hack workarounds into it to get it to function
> > doesn't mean we should continue to use it.
> >
> 
> You misunderstand me. I wasn't arguing that GPT wasn't perhaps more
> elegant than MBR and dos partitions. I wanted to know what was
> _fragile_ about MBR. Completely different things.

I did answer (somewhat obliquely).

mbr as a single isolated unit is not especially fragile; very little
software is and bits don't magically "rot"

It's the system into which the sysadmin inserts mbr that is fragile.
The whole system is fragile like an egg is fragile - it can't withstand
much manhandling or moving of stuff around before some mistake wreaks
everything, and that is mostly due to mbr's limits.

It's not semantic nitpicking here, if the system as a unit becomes
fragile as a result of part X, then the system is still fragile.

-- 
Alan McKinnon
alan.mckinnon@gmail.com

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[J.Marcos Sitorus]

Hi guys, after quick read about ssd, I have a couple of question:
1. My friend have new server with a ssd installed. He plan to RHEL 5.7
(I don't know why he choose this) on it. On redhat website, it say
something like this:
"However, if the device does not export topology information, Red Hat
recommends that the first partition be created at a 1MB boundary."
What does it mean by 1MB boundary? Does it mean he have to create 1MB
free space in front or he have to create a 1MB partition in front of
his actual partition(s)?

2. Is it possible to combine TRIM support and ext3 partition (AFAIK,
RHEL 5.7 haven't support ext4)?

*i hope this is not count as hijacking

On 8/14/12, Alan McKinnon <alan.mckinnon@gmail.com> wrote:
> On Mon, 13 Aug 2012 11:55:31 -0400
> Michael Mol <mikemol@gmail.com> wrote:
>
>> On Mon, Aug 13, 2012 at 11:47 AM, Alan McKinnon
>> <alan.mckinnon@gmail.com>wrote:
>>
>> > On Mon, 13 Aug 2012 08:17:23 -0400
>> > Michael Mol <mikemol@gmail.com> wrote:
>> >
>> > > 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?
>> >
>> > it's 30 years old,
>> > only 4 primary partitions,
>> > only 16 extended partitions,
>> > it's got that weird DOS boot flag thing,
>> > it all has to fit in one sector.
>> >
>> > I had to fix a mispartitioned disk over the weekend, this really
>> > should have been a simple mv-type operation, but because all 4
>> > primary partitions were in use I had to disable swap and use it as
>> > a leap-frog area. It felt like I was playing 15 pieces with the
>> > disk. That's fragile - not that the disk breaks, but that it breaks
>> > my ability to set the thing up easily.
>> >
>> > Basically, mbr was built to cater for the needs of DOS-3. In the
>> > meantime, 1982 called and they want their last 30 years back.
>> >
>> > Just because we can hack workarounds into it to get it to function
>> > doesn't mean we should continue to use it.
>> >
>>
>> You misunderstand me. I wasn't arguing that GPT wasn't perhaps more
>> elegant than MBR and dos partitions. I wanted to know what was
>> _fragile_ about MBR. Completely different things.
>
> I did answer (somewhat obliquely).
>
> mbr as a single isolated unit is not especially fragile; very little
> software is and bits don't magically "rot"
>
> It's the system into which the sysadmin inserts mbr that is fragile.
> The whole system is fragile like an egg is fragile - it can't withstand
> much manhandling or moving of stuff around before some mistake wreaks
> everything, and that is mostly due to mbr's limits.
>
> It's not semantic nitpicking here, if the system as a unit becomes
> fragile as a result of part X, then the system is still fragile.
>
> --
> Alan McKinnon
> alan.mckinnon@gmail.com
>
>
>


-- 
Salam,

J.Marcos S.
Sent from X1™

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Paul Hartman]

On Tue, Aug 14, 2012 at 9:33 PM, J.Marcos Sitorus <gkjdsh@gmail.com> wrote:
> Hi guys, after quick read about ssd, I have a couple of question:
> 1. My friend have new server with a ssd installed. He plan to RHEL 5.7
> (I don't know why he choose this) on it. On redhat website, it say
> something like this:
> "However, if the device does not export topology information, Red Hat
> recommends that the first partition be created at a 1MB boundary."
> What does it mean by 1MB boundary? Does it mean he have to create 1MB
> free space in front or he have to create a 1MB partition in front of
> his actual partition(s)?

When you run fdisk and it asks starting sector, choose one that has
1MB of free space in front of it. Flash memory, like magnetic disks,
writes and erases in blocks, so improper alignment can cause multiple
read/writes to happen when only one should have been necessary. Most
flash-based memory has erase blocks with multiples of 4MB so I always
begin the partition at 4MB to be safe. Magnetic disks have much
smaller blocks so 1MB is the usual recommendation for those (since 1MB
is safely divisible by 64k/32k/16k/8k/512b etc.) though if you know
the actual block size on your disk you can go smaller than 1MB.

> 2. Is it possible to combine TRIM support and ext3 partition (AFAIK,
> RHEL 5.7 haven't support ext4)?

Basically no. Depending on kernel & everything else version there
might be offline trim support ioctl, but not automatic. Don't know
anything about RHEL but maybe xfs supported TRIM in that version.

> *i hope this is not count as hijacking

Don't know if it is hijacking, but it is not an RHEL list, and
top-posting can get an angry mob started. :)

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Mick]

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On Wednesday 15 Aug 2012 17:42:02 Paul Hartman wrote:
> On Tue, Aug 14, 2012 at 9:33 PM, J.Marcos Sitorus <gkjdsh@gmail.com> wrote:
> > Hi guys, after quick read about ssd, I have a couple of question:
> > 1. My friend have new server with a ssd installed. He plan to RHEL 5.7
> > (I don't know why he choose this) on it. On redhat website, it say
> > something like this:
> > "However, if the device does not export topology information, Red Hat
> > recommends that the first partition be created at a 1MB boundary."
> > What does it mean by 1MB boundary? Does it mean he have to create 1MB
> > free space in front or he have to create a 1MB partition in front of
> > his actual partition(s)?
> 
> When you run fdisk and it asks starting sector, choose one that has
> 1MB of free space in front of it. Flash memory, like magnetic disks,
> writes and erases in blocks, so improper alignment can cause multiple
> read/writes to happen when only one should have been necessary. Most
> flash-based memory has erase blocks with multiples of 4MB so I always
> begin the partition at 4MB to be safe. Magnetic disks have much
> smaller blocks so 1MB is the usual recommendation for those (since 1MB
> is safely divisible by 64k/32k/16k/8k/512b etc.) though if you know
> the actual block size on your disk you can go smaller than 1MB.
> 
> > 2. Is it possible to combine TRIM support and ext3 partition (AFAIK,
> > RHEL 5.7 haven't support ext4)?
> 
> Basically no. Depending on kernel & everything else version there
> might be offline trim support ioctl, but not automatic. Don't know
> anything about RHEL but maybe xfs supported TRIM in that version.
> 
> > *i hope this is not count as hijacking
> 
> Don't know if it is hijacking, but it is not an RHEL list, and
> top-posting can get an angry mob started. :)

Grrrrr!  :@

LOL!

Anyway, I am told that Gparted now adds a 1M unallocated space before a 
partition is created (and shows it too) as long as one leaves the default 
alignment option of 'MiB', rather than 'cylinders'.

I'm not sure what it does if you select cylinders.  May still create it, but I 
seem to recall that older versions of Gparted did not show unallocated space 
less than 8M.

I think that current versions of fdisk also provide a 1M boundary, or is it 
4M?  Someone more up to speed on this can comment.
-- 
Regards,
Mick

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Paul Hartman]

On Wed, Aug 15, 2012 at 3:48 PM, Mick <michaelkintzios@gmail.com> wrote:
>
> I think that current versions of fdisk also provide a 1M boundary, or is it
> 4M?  Someone more up to speed on this can comment.

I think basically everything* except for cfdisk defaults to 1M boundary now.

* "everything" meaning fdisk, gdisk, parted, gparted...

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Neil Bothwick]

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On Wed, 15 Aug 2012 16:14:50 -0500, Paul Hartman wrote:

> > I think that current versions of fdisk also provide a 1M boundary, or
> > is it 4M?  Someone more up to speed on this can comment.  
> 
> I think basically everything* except for cfdisk defaults to 1M boundary
> now.
> 
> * "everything" meaning fdisk, gdisk, parted, gparted...

... and cgdisk.


-- 
Neil Bothwick

Multitasking: Reading in the bathroom.

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Re: [gentoo-user] new installation (ssd, new udev, grub2)

[J.Marcos Sitorus]

Hi Paul,
Thanks. So to be on safe side, he should partitioned the SSD using the
latest fdisk (booting from sysrescuecd?) and it will automatically
align to 1MB, right?

> Don't know if it is hijacking, but it is not an RHEL list, and
> top-posting can get an angry mob started. :)
Sorry about top-posting, I use quick reply from gmail :p

-- 
Salam,

J.Marcos Sitorus
Sent from X1™

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Paul Hartman]

On Thu, Aug 16, 2012 at 2:51 AM, J.Marcos Sitorus <gkjdsh@gmail.com> wrote:
> Hi Paul,
> Thanks. So to be on safe side, he should partitioned the SSD using the
> latest fdisk (booting from sysrescuecd?) and it will automatically
> align to 1MB, right?

Yes, I think util-linux 2.17 or higher will support this (might be
dependent on kernel version as well, but any live CD made in the the
past year should contain this for sure)

Re: [gentoo-user] new installation (ssd, new udev, grub2)

[Pandu Poluan]

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On Aug 16, 2012 2:57 PM, "J.Marcos Sitorus" <gkjdsh@gmail.com> wrote:
>
> Hi Paul,
> Thanks. So to be on safe side, he should partitioned the SSD using the
> latest fdisk (booting from sysrescuecd?) and it will automatically
> align to 1MB, right?
>
> > Don't know if it is hijacking, but it is not an RHEL list, and
> > top-posting can get an angry mob started. :)
> Sorry about top-posting, I use quick reply from gmail :p
>

For SSD, it's even recommended to leave a space of 4 MB before the first
partition.

Rgds,

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