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

[Paul Hartman]

On Tue, Aug 14, 2012 at 9:33 PM, J.Marcos Sitorus <gkjdsh@×××××.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. :)