Date: Tue, 21 Aug 2001 16:48:25 -0700 (PDT) From: Hodge Podge <nicole@unixgirl.com> To: Michael VanLoon <MichaelV@EDIFECS.COM> Cc: Borja Marcos <borjamar@sarenet.es>, freebsd-hardware@freebsd.org, mike.wentz@3ware.com, val@picturetrail.com Subject: RE: 3ware stuff not ready for heavy duty useage-followup Message-ID: <XFMail.010821164825.nicole@unixgirl.com> In-Reply-To: <36F7B20351634E4FBFFE6C6A216B30D54CAA@ecx1.edifecs.com>
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On 21-Aug-01 Michael VanLoon wrote: >> From: Hodge Podge [mailto:nicole@unixgirl.com] >> Sent: Monday, August 20, 2001 6:38 PM >> >> On 20-Aug-01 Michael VanLoon wrote: >> > I seriously doubt the average 300W power supply is going to reliably > power >> > your computer and that many disks. You might check into trying one of > the >> > Enermax EG651P power supplies which would supply a much more stable > amount >> > under heavy load. Other high-load power supplies might work as well. > That >> > 400 might be OK, but quality construction is important too -- some cheap >> > generic 400 might not be any better than the others. Check with PC > Power >> > and Cooling, SuperMicro, etc. for suitable power supplies. >> >> No, 300 watts is plenty. IDE's do not use as much current as SCSI drives > and I >> have run more scsi drives than that on a 300W Power supply. >> >> Now I suppose it would depend on the amount of activity and the drives >> particular sensitivity, but that only makes the case more so in some ways. > How >> much coddling do the IDE's need then? > > Well yes and no. First it depends how much power your system itself is > pulling. Don't forget that AMD recommends a minimum of 300W power supply > for just your average desktop with only one or two drives. Intel chips suck > up less, but in some cases not significantly less. > > Now you may be right in some cases. I decided to go look at the Maxtor and > IBM sites. It seems under peak load, considering worst-case (highest > electrical running load) on eight drives (I think that was your biggest > set-up) you get a power draw of: > > Maxtor DiamondMax Plus 60: > 4.80 Amps at 12V > 4.40 Amps at 5V > > IBM 60GXP: > 5.36A at 12V > 3.92A at 5V > > These are for average load. I think Maxtor doesn't actually print true peak > because IBM's is quite a bit higher than these. At peak loads: > > IBM 60GXP: > 16.00A at 12V!! > 9.04A at 5V > > Remember that's 16A for the hard drives alone, not counting any other stuff > installed in your computer. > > Someone mentioned having problems with starting the system properly. Here's > maybe why... look at these spin-up currents: > > Maxtor DiamondMax Plus 60: > 23.60A at 12V!!! > 3.44A at 5V > > IBM 60GXP: > 16.00A at 12V!! > 6.4A at 5V > > > The quality Enermax power supplies are a good place to look for some > guidance on this. Remember that cheap no-name power supplies are typically > going to handle this worse than well-made ones will. Their 300W model > (EG301P) has a max output rating of 15A at 12V. This means that if all > eight drives try to spin up at once, you are over-loading the power supply. > This can result in startup errors. But even as indicated above, if all > eight drives are doing full seek traffic all at once, even that might push > you above the power supply ratings (16A on drives > 15A on power supply). > > And remember this is only the drives -- this doesn't count other stuff > drawing 12V inside your case. Since the CPU and motherboard circuitry use > the 3.3V and 5V taps, this likely will not crash your machine, but will > cause hard drive errors. > > Even Enermax's biggest power supply, the 550W unit (EG651P) is just barely > capable of providing enough power for simultaneous spin-up of all eight > Maxtor drives (23.6A on drives just barely < 24A from PS). And that's > assuming you don't have more than 0.4A draw on 12V from everything else in > your system. > > So your assumption, "300 watts is plenty," doesn't necessarily bear itself > out. Now if you use things like staggered spin-up, that will help alleviate > problems with every drive trying to suck down spin-up current at the same > time, but even with that, your full-load performance is just barely over the > limit of this particular power supply. Assuming "no, it's plenty" without > any real proof is an invitation to disaster in my book. I see.. So what you are saying is then that all those people who make and sell systems with that many HD's more or less are all asking for trouble? That all the scsi systems I have built or seen running similiarly and without errors anywere near this are just lucky? So you postulate that if I replace my 400 watt power supply with a 400 Watt "better" power supply, I will no longer have problems with the 3ware card under heavy loads? I know my boss is not sinking another dime into IDE stuff until proven safe. So.. Anyone have a power supply they belive will handle the load they can loan me for testing? I'm game? What would you say if I told you that the power supply in the case was an Enermax power supply? Nicole >> >> >> From: Hodge Podge [mailto:nicole@unixgirl.com] >> >> Sent: Sunday, August 19, 2001 2:20 PM >> >> >> >> On 19-Aug-01 Borja Marcos wrote: >> >> > On Sunday 19 August 2001 09:10, you wrote: >> >> > >> >> >> Yup, cables that were supplied by 3ware. In 3 2 or 3 >> >> different cases >> >> >> and power supplies. Each were 300 or 400 watt power supplies. >> >> > >> >> > Excuse me for stepping into the discussion, but I >> >> think this is an >> >> > important issue: Which was the brand of the cases, power >> >> supplies and >> >> > fans? How much did they cost? Nowadays the choice of a good >> >> case and power >> >> > supply is as important as the choice of a good cabling, >> disks, etc. >> >> >> >> One of the cases was from Silicon-rax and had a 300 watt >> >> power supply. The >> >> other cases were from (I think) acmemicro and one had a 300 >> >> watt power supply >> >> and the other a 400 watt power supply. (don't know the makes >> >> of any of the >> >> supplies. ******* |\ __ /| (`\ ******* * * | o_o |__ ) ) * * * * // \\ * * * Nicole Harrington | AKA Hodge Podge * ----------------------(((---(((-------------------------------- nicole@unixgirl.com http://www.unixgirl.com/ webmistress@dangermouse.org http://www.dangermouse.org/ nicole@deviantimages.com http://www.deviantimages.com/ -- Powered By Coca-Cola and FreeBSD -- "The world is run by those who show up" -- The Best Place for Your Web Site - www.WebWeaver.net -- ---------------------------------------------------------------- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message
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