From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Zhang Subject: RE: More tales of horror from the linux (HW) raid crypt Date: Thu, 23 Jun 2005 08:31:47 -0400 Message-ID: <1119529907.5503.1.camel@localhost.localdomain> References: <200506230305.j5N35u222988@www.watkins-home.com> Reply-To: mingz@ele.uri.edu Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-U0tS4vXuYy1zmmFYuvIG" Return-path: In-Reply-To: <200506230305.j5N35u222988@www.watkins-home.com> Sender: linux-raid-owner@vger.kernel.org To: Guy Cc: bdameron@pivotlink.com, linux-raid@vger.kernel.org List-Id: linux-raid.ids --=-U0tS4vXuYy1zmmFYuvIG Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2005-06-22 at 23:05 -0400, Guy wrote: > > -----Original Message----- > > > > > > > will this 24 port card itself will be a bottleneck? > > > > > > > > ming > > > > > > Since the card is PCI-X the only bottleneck on it might be the Proces= sor > > since > > > it is shared with all 24 ports. But I do not know for sure without > > testing it. > > > I personally am going to stick with the new 16 port version. Which is= a > > PCI- > > > Express card and has twice the CPU power. Since there are so many > > spindles it > > > should be pretty darn fast. And remember that even tho the drives are > > 150MBps > > > they realistically only do about 25-30MBps. > >=20 > > the problem here is taht each HD can stably deliver 25-30MBps while the > > PCI-x will not arrive that high if have 16 or 24 ports. i do not have a > > chance to try out though. those bus at most arrive 70-80% the claimed > > peak # :P >=20 > Maybe my math is wrong... > But 24 disks at 30 MB/s is 720 MB/s, that is about 68.2% of the PCI-X > bandwidth of 1056 MB/s. yes, u math is better. >=20 > Also, 30 MB/s assumes sequential disk access. That does not occur in the > real world. Only during testing. IMO yes, only during test. but what if people build raid5 base on it, this is probably what people do. and then a disk fail? then a full disk sequential access becomes normal. and disk fail in 24 disk is not so uncommon. >=20 > Guy >=20 > >=20 --=-U0tS4vXuYy1zmmFYuvIG Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.6 (GNU/Linux) iD8DBQBCuquySYbkL5BnVYoRAjsvAJ9f6ghLfwA0h/9ABEAJUXTPbLVqggCfejNP WYUnTniaqHMHwpjmpUmYVGs= =/kKi -----END PGP SIGNATURE----- --=-U0tS4vXuYy1zmmFYuvIG--