Date: Sun, 20 Jun 2010 12:50:03 -0600 From: Scott Long <scottl@samsco.org> To: "Steven Hartland" <killing@multiplay.co.uk> Cc: oizs <oizs@freemail.hu>, freebsd-current@freebsd.org Subject: Re: Dell Perc 5/i Performance issues Message-ID: <A799F335-8EA0-4A3D-9A96-A8BE4F1C9D5B@samsco.org> In-Reply-To: <0B4F09B43AE84F24954E3B940FA0ECBB@multiplay.co.uk> References: <4C1AB4C0.4020604@freemail.hu> <A594C946-32C0-4C4A-AA37-0E81D270162A@mac.com> <4C1B3792.9000007@freemail.hu><AANLkTimsHZLREByndqXEjt2yjdvOYVV7Rnw8AMjqxYIl@mail.gmail.com><4C1C0ED9.8090103@freemail.hu> <2F904ED8-BC95-459F-8536-A889ADDA8D31@samsco.org> <0B4F09B43AE84F24954E3B940FA0ECBB@multiplay.co.uk>
next in thread | previous in thread | raw e-mail | index | archive | help
I just set up a machine with the following GPT scheme:
=3D> 34 5853511613 mfid0 GPT (2.7T)
34 128 1 freebsd-boot (64K)
162 862 - free - (431K)
1024 2097152 2 freebsd-ufs (1.0G)
2098176 4194304 3 freebsd-swap (2.0G)
6292480 2097152 4 freebsd-ufs (1.0G)
8389632 104857600 5 freebsd-ufs (50G)
113247232 5740264414 6 freebsd-ufs (2.7T)
5853511646 1 - free - (512B)
After the first partition, I created a deliberate gap for alignment, =
reflected in the second line. The third line shows a starting offset of =
sector 1024, which is 512KB. This should be a good generic start point =
for most RAID geometries with a stripe size <=3D 512KB. The rest are =
normal /, swap, /var, /usr and /opt partitions. The single free sector =
on the final line is probably a calculation error on my part, there's no =
particular reason for it.
The gpart man page has good descriptions on how to create partitions and =
make the GPT scheme bootable. It's not very automated, you'll need to =
have a calculator handy, but it works.
Scott
On Jun 20, 2010, at 12:20 PM, Steven Hartland wrote:
> Does anyone know of a nice how to guide for achieving this?
>=20
> ----- Original Message ----- From: "Scott Long" <scottl@samsco.org>
> 2. Partition alignment. If you're using classic MBR slices, =
everything gets misaligned by 63 sectors, making it impossible for the =
controller to optimize both reads and writes. If the array is used for =
secondary storage, simply don't use an MBR scheme. If it's used for =
primary storage, try using GPT instead and setting up your partitions so =
that they are aligned to large power-of-2 boundaries.
>=20
>=20
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> This e.mail is private and confidential between Multiplay (UK) Ltd. =
and the person or entity to whom it is addressed. In the event of =
misdirection, the recipient is prohibited from using, copying, printing =
or otherwise disseminating it or any information contained in it.=20
> In the event of misdirection, illegible or incomplete transmission =
please telephone +44 845 868 1337
> or return the E.mail to postmaster@multiplay.co.uk.
>=20
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?A799F335-8EA0-4A3D-9A96-A8BE4F1C9D5B>