From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phil Turmel Subject: Re: md RAID with enterprise-class SATA or SAS drives Date: Thu, 10 May 2012 17:41:29 -0400 Message-ID: <4FAC3609.9030600@turmel.org> References: <4FAAE8F1.8000600@pocock.com.au> <4FABC7C6.4030107@turmel.org> <4FAC2FF2.5060305@hardwarefreak.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4FAC2FF2.5060305@hardwarefreak.com> Sender: linux-raid-owner@vger.kernel.org To: stan@hardwarefreak.com Cc: Marcus Sorensen , Daniel Pocock , linux-raid@vger.kernel.org List-Id: linux-raid.ids On 05/10/2012 05:15 PM, Stan Hoeppner wrote: > On 5/10/2012 8:51 AM, Phil Turmel wrote: > >> Hardware RAID cards usually offer battery-backed write cache, which is >> very valuable in some applications. I don't have a need for that kind >> of performance, so I can't speak to the details. (Is Stan H. >> listening?) > > Yes, I'm here to drop the hammer, and start a flame war. ;) I've been > lurking and trying to stay out of the fray, but you "keep dragging me > back in!" --Michael Corleone Mission Accomplished! I am very interested in what professionals like you recommend, even if I am not in a position to buy the pieces. > I find the mere existence of this thread a bit comical, as with all > others that have preceded it. I made the comment on this list quite > some time ago that md raid is mostly used by hobbyists, and took a lot > of heat for that. The existence of this thread adds ammunition to that > argument. I think it is just us hobbyists who suffer these problems, trying to get the most out of our limited budgets. At least we are brightening your day with comedy. > If not for the fact Western Digital added "TLER" to the spec sheet of > it's RE and Raptor series drives many years ago, nobody would have every > mentioned it. > > WD did this because those in the "channel" marketplace weren't buying > the drives. They saw no difference with these new "enterprise" drives > but the much higher price. WD has never sold RE/Raptor drives to > server/storage OEMs. WD has never had a presence in enterprise storage. > Seagate, Hitachi/IBM, Fujitsu, and to a small degree Toshiba, have > owned that space for over a decade. > > So in an attempt to drive sales, they added "TLER" to the sheet to > differentiate from their desktop drives. So what happens? All the > hobbyists immediately want to enable this "TLER" feature from the > "enterprise" drives on their consumer models, because "TLER" is all that > makes them "enterprise" drives, after all, "all WD drives are the same, > just with different firmware, right?". > > Proof point: Few write about this subject using the generic term "ERC", > which is used by Seagate, or the term Samsung uses, "CCTL". Everyone > seems to talk about "TLER". Hmmm... Coincidence? No, marketing. I won't argue with successful marketing. More power to them. Of course, they aren't offering this in their more affordable products, so me and my well-informed hobbyist compatriots won't be buying them either. I learned ERC before TLER, not that it matters much. > You won't find a single discussion about ERC/TLER/CCTL on any enterprise > storage forum, unless its brought up by someone desiring to cut cost > corners using consumer drives. Exactly. But that doesn't provide evidence either way as to software raid use in enterprises. > So if md raid is not limited to use by hobbyists, and is indeed used in > enterprise environments, then why aren't the enterprise boys discussing > "the problems w/TLER and enterprise drives"? Because obviously md raid > has no issues when being used with enterprise (ERC/TLER/CCTL) drives. > > Either that, or md raid is only used by hobbyists. ;) Well, it is definitely used by us hobbyists. :-) Phil