Partitions alignment question

English Install/Boot/Login
1

Just a quick question concerning SSDs before I pull the trigger on 12.1. Will YAST during installation automatically align the suggested partitions to lets say 1mb or 512kb? If not do I need to use something like fdisk before hand or the “expert settings” in yast are capable of this? Where to look for alignment options if I wanna manually partition the disc during installation?
Is it recommended to “secure erase” the SSD first before I install linux(ext4) ? Or a simple reformat is gonna be enough?

And to add to this - I have two other disc drives that are formatted with NTFS. Will you recommend going for ext4 everywhere or it’s considered save to use them as is? I’ve heard about some write support but don’t know how reliable it is? I’m probably going to mount them somewhere in /home as additional storage. Or are there some more clever ways for using multiples drives? Logical Volume Manager looks interesting but I don’t think it intended for mixing 2 different types of drives.

Thanks!

2

Hi,

did you mean to use your SSD as a drive on its own,
or did you mean to use it for the ‘Smart Response Technology’
of the later mainboards for Intel processors ?

As far as I know, the latter isn’t truely supported by Linux yet.

Mike

3

I’m planning to use it as a stand alone drive. Probably gonna make to partitions for / and /home and later decide what to do with the other hard drives I have.

I’m just not sure whether i need to manually align the partitions or they will be okay?

4

Never use non native Linux file systems (like NTFS) for your Linux system. Linux is able to use those file systems so you can exchange data with other systems, but NTFS and the like fail to have a lot of the features you need for a safe consistent Linux.

5

ssaatt wrote:
> Just a quick question concerning SSDs

Sorry, I don’t know anything about SSDs.

> And to add to this - I have two other disc drives that are formatted
> with NTFS. Will you recommend going for ext4 everywhere or it’s
> considered save to use them as is? I’ve heard about some write support
> but don’t know how reliable it is?

If they will only be used with Linux, reformat them to a native format.
Consider having specific transfer partitions if you also use Windows. Or
use a separate server and samba.

> I’m probably going to mount them
> somewhere in /home as additional storage. Or are there some more clever
> ways for using multiples drives? Logical Volume Manager looks
> interesting but I don’t think it intended for mixing 2 different types
> of drives.

Yes, LVM will happily mix as many different types and sizes of drives
(actually, partitions) as you give it. IMHO, it’s a good way of managing
a multi-drive setup. You can also layer RAID (mdadm) below it.

Cheers, Dave

6

Hi again,

Fine, so in general this should work. Don’t forget about the swap partition, for which the SSD probably will be an especially good place.

With respect to the aligment what I know can be summarized as follows.

For a long time blocks on harddisks (HDs) had a size of 0.5 kB (or 512 Bytes).

As a bad habit, in older systems, the first partition on a harddisk was usually aligned starting
from an odd block number.

If your HD internally had a block size of 512 Bytes, this never resulted in problems or a slowdown.

As the size of the HDs grew, some models emerged, that internally worked with blocks
that were larger than 512 Bytes (e.g. 4096 Bytes), while still pretending externally that they
would be devices with blocks of 512 Bytes size.

Then it in fact posed a problem and resulted in a slowdown, if a pratition was aligned at an
odd sector number based on a block size of 512 Bytes.

There never has been a sector size for HDs lower than 512 Bytes (at least as far as I know),
so your question whether the suse/linux partitioner would align your partitions to
512 Byte blocks in any case can only be: Yes.

It’s more than likely that your SSD is organized in blocks of 512 Bytes (or physically in even
smaller blocks), so there wouldn’t be any problem.

If you doubt that, you might take a look into the manuals of this SSD try some tool
if it isn’t disclosed there.

In more recent OSs the blocks are usually aligned to even 4096 Byte blocks.
But I’m not a Linux guru, and don’t know enough about the interna of the partitioner
or the installer that come with openSUSE.

Good luck
Mike

7

forgot sth.:

using LVM in your case may not be wise:

as far as I know it gets different then to predetermine to which physical device
the data goes.

You will want to use your SSD to speed up the system, so you have a clear
interest in making sure that your / partition and possible your /home partition
are physically located on the SSD.

Cheers to all !

8

… sorry, seems I’ve been a bit too quick here:

I later on checked against the contents of a recent article in a computer journal on SSDs & Linux.

Corrections / extra precautions with SSDs:

(i) Corrections (alignment):
Versions of Gparted included in recent major distros of Linux (as well as w. starting from Vista)
seem to align partitions to a block size/sectors of 1 MB, which is about 2000 times 512 Bytes (or 0.5 kB).

For older SSDs it partly had been recommended to align partitions to the memory pages of these devices.

(ii) Extra precautions with SSDs:
This goes beyond the topic of this thread, so just a few words:

Other than usual HDs, SSDs like to be informed about unused space,
in order to increase the SSDs life expectancy and speed.
For this ‘fstrim’ can be used, called sporadicly from the (Linux!) command line,
or as a cron job.
For ext4 this is supported starting from Kernel 2.6.37,
for ext2, ext3, and XFS starting from Kernel 2.6.38,
for Btrfs starting from Kernel 2.6.39.

For swap partitions either swapon -d or or the fstab option ‘discard’ should be used,
to achieve the same.

Mike