From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Haigh Subject: Re: RAID6 - whole disk vs partitions Date: Sun, 20 Dec 2015 09:21:33 +1100 Message-ID: <5675D86D.3000403@crc.id.au> References: <56756AF1.7050005@crc.id.au> <5675BFBE.5060604@turmel.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="pJKm6VcvRrJU2eVcO6s62Q4LkbUQEInoe" Return-path: In-Reply-To: <5675BFBE.5060604@turmel.org> Sender: linux-raid-owner@vger.kernel.org To: Phil Turmel , linux-raid@vger.kernel.org List-Id: linux-raid.ids This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --pJKm6VcvRrJU2eVcO6s62Q4LkbUQEInoe Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 20/12/15 07:36, Phil Turmel wrote: > Hi Steven, >=20 > On 12/19/2015 09:34 AM, Steven Haigh wrote: >=20 >> I've always used the whole disk for the RAID6 - as from what I >> understand, this gives the best layout for various drives - no matter = if >> they're 512 or 4096 byte sectors. >> >> Is this still the case? >=20 > There's no real advantage other than an itty bit of space. If my case > was too small to have a separate mirror for my OS, I'd make three > partitions on everything for boot, LVM root & etc (raid10), and bulk > storage (raid6). When I have room for the mirrored OS (boot & LVM), I > use whole disks for the bulk storage. Yes, I have two separate disks in RAID1 as the boot / VM guests - the RAID6 is used for bulk storage. The chassis has a total of 10 hot swap bays, with 5 used by the RAID6, 2 by the RAID1 and 3 spare. I get resync speeds of around 170Mb/sec on the RAID1. >> I've noticed that my resync speeds on this RAID6 hover around 60Mb/sec= - >> which I was expecting to be a bit quicker (although I haven't tested >> speeds on this array for years). >=20 > Consider using small chunk sizes for parity raid if there's even the > slightest random access usage. See the list archives for the past > couple weeks for a long thread on performance. There's many > optimization possibilities. I have tried to keep up with those couple of threads - but I've found it hard to follow across the length of time they've been going. A summary of the findings in those threads with experimentation would be fantastic!= It seems that actual data beyond "increase --setra on /dev/sd[.] and increase the stripe_cache_size is about all I find via Google - and that data is years old... --=20 Steven Haigh Email: netwiz@crc.id.au Web: https://www.crc.id.au Phone: (03) 9001 6090 - 0412 935 897 --pJKm6VcvRrJU2eVcO6s62Q4LkbUQEInoe Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJWddhxAAoJEEGvNdV6fTHc6dAQAKD3IKKtJMr6bMb2zntjmrKp VSjjg/6lRf3TBgyA6GQrWKTYS17vNnW23RJIlePYso489yQNcCta4Iqvgk6mSgVu O2WPAn9+xTllaZcjIUlVnVv402URlmJorqNPUol76FHn4Njk9Kcwkwqy9fzk+r19 smNp7XSIibp9M8idsUMwQe73ylKR566JO0LfyqsTDxMEU/zW7AccUare9iFVBA0t KSrWiUp7F1uZ4QRtqmws7DOPfQrHGEXg5bOdynt+Ms//ck+/8Mi+secSx3kfdPsW 3IzSQ5WgyVrxk23FHQ26xhv+AKrxJM+SLQfX4V+vRoCNBsmE8Xp1DO9bbDjXUG+t 7z2if0CsnBwpwVpkBuOzSxn6/eDWchCbniwNJZzh5m2D3OlT6UidkEwgQTLon0on 2cwcAgMrSL1NPo/OnCR8Na1+o5vAjt1a+gRybcXJyuf1df/004k1Ta3sG5ynkzj4 gtCO4XQQ+jOubb9VAcqYTXCfXqvt6opZzYAAbdJIa9s7UpUYEFXpP86UEZhCmuX5 ZhS+F33FbIdoJSoR74Dygm+XXoQzES7fgMTEVVFWAaPM2gCzeWyh7ujoV7kDvSXK 0abhO51/RUyIG0snYgqcwlTqBSUiesqtB51HDljkZ6YZdvzH84I+mUL96Ihgan1S YmLOnlQfHUFbS8loB/+Q =ilHx -----END PGP SIGNATURE----- --pJKm6VcvRrJU2eVcO6s62Q4LkbUQEInoe--