[CentOS] Serial ATA hardware raid.

Sat Apr 16 00:37:39 UTC 2005
William Warren <hescominsoon at emmanuelcomputerconsulting.com>

I would be interested in the informaiton that WD outsources their 
manufacturing to other drive makers please..:)

Bryan J. Smith wrote:

> From:  Franki 
> 
>>After abit of searching,
>>I found a 4 port 8506 for retail $480 here:
> 
> 
> BTW, when I was estimating prices earlier, I was using US$.
> 
> 
>>For the record, this machine is to replace a web server with about 60+ 
> 
> domains hosted,
> 
> I've been maintaining Linux DNS/SMTP servers since just before Apache surfaced, adding CERN httpd and the "patchy."
> But the majority of my Linux deployment has been for file servers - especially NFS as of 1999.
> I still prefer Fujitsu SPARC/Solaris and, even more so, NetApp filers as NFS/SMB plarforms,
> but throwing around TBph is typical.
> 
> 
>>some of which get allot of hits,
>>most are dynamic 
> 
> (Perl/PHP/Java) and the
> 
>>server runs local MySQL/PostgreSQL as well.
> 
> 
> I feel very strongly about using RAID-0+1 in this configuration if you can afford to reduce your effective storage by 33% over RAID-5.
> But the choice is yours.
> You're not going to make a massive hit since CPU and network is more important.
> But you should still segment network and storage with an AMD8131 HyperTransport tunnel that provides seperate PCI-X channels for each.
> And don't skimp on the NIC - get something with at least 256KB SRAM receive cache.
> 
> 
>>I don't think speed is as important as redundancy,
> 
> 
> RAID-0+1 means you could possibly lose 2 discs and be okay, although there's no guarantee after losing 1.
> The other thing 3Ware does is read interleaving between the two mirrors.
> 
> 
>>but having said that, for future proofing,
>>I'd like to get a good performer as well.
> 
> 
> 3Ware's ASIC compared to a Microcontroller is like comparing a layer-2 ASIC+SRAM switch to a PC CPU+DRAM that does switching/routing.
> The ASIC can do it much faster, although the PC can buffer more.
> So it depends if you're just throwing data around like layer-2 switching (switching RAID-0, 1, 0+1 reads/writes),
> or if you are calculating dynamic routes in non-real-time (like RAID-5 XORs for parity).
> That's why 3Ware calls it a "storage switch."
> 
> Of course if you have a 9500, it has DRAM too, so it's like having a layer-3 switch (that can route too).
> And without the inefficiency of the PC interconnect.
> 
> 
>>Which brings up another question,
>>I was looking at populating this thing 
>>with 10,000 RPM 8MB cache 40gig (roughly) drives,
>>but the only drives I 
> 
> see in my pricelists that
> 
>>match those specs are Western Digital 
> 
> Wd360GB's
> 
>>and I generally have stayed away from WD drives in the 
>>past due to dodgy standards implimentation
>>and the problems that can cause with Linux,
> 
> 
> First, other than Maxtor, Seagate and Hitachi, no one makes their own drives.
> WD taps the first and last for many, and Maxtor's approch is different than Seagate and Hitachi (I'll send you a link to any explaination).
> 
> Secondly, the ATA drives *never* talk to the system, only the 3Ware ASIC.
> And unlike GPL Linux, 3Ware can get proprietary command set info from vendors.
> I have *never* had a "DMA timeout" in the history of my 6-year 3Ware  usage.
> 
> 
>>should I continue to stay away?
> 
> 
> WD's 10,000rpm drives come off the same "enterprise" line as Hitachi's SCSI/SATA.
> They are not commodity at all.
> Hitachi and Seagate have dedicated "enterprise" lines for some SCSI/SATA,
> and then "commodity" lines for SCSI/SATA/ATA.
> Maxtor has only one line and then tests for tolerance and those that rate high are then declared "enterprise" with a 3-5 year warranty.
> 
> 
>>Actually, now that I think about it,
>>I guess 10,000 rpm drives with raid is probably over kill for my usage,
> 
> 
> Actually, since you are more concerned with latency in your application,
> then a faster spindle is better.
> In reality, the higher the density, typically the higher the DTR.
> So it is very common to see lower density or 1-gen back of higher spindles have a *lower* DTR than a lower spindle.
> 
> 
>>but they are pretty cheap anyway, (149 AUD each) but
>>if WD are still dodgy
> 
> 
> I have WD 40, 80 and 160 "consumer" ATA/SATA drives that give some chipsets fits under Linux,
> but 0 issues on a 3Ware card.
> 
> 
>>then I'd probably go for 
> 
> 7200rpm seagates
> 
>>as I can get the 8MB 80gig 7200rpm drives for $85 AUD.
> 
> 
> Seagate is the only manufacture giving 3-5 year warranties on their "consumer" drives instead of 1-3.
> Yes, they cost 10-20% more than Maxtor/WD, but that's piece-of-mind IMHO.
> 
> The "sweet spot" right now seems to be 200GB (160-250GB) for size, density (DTR performance) and price (sub-US$100).
> (4) 200GB = 400GB effective RAID-0+1.
> 
> 
> 
> 
>>Are Western Digitals still dodgy?
> 
> 
> All "integrated drive electronics" (IDE) drives via Advanced Technology (AT) Attachment (ATA) seem to do a poor job of following ATA-5 and ATA-6 specs.
> But with 3Ware, I've yet to have an issue.
> I even have 80GB WDs on old 3Ware 6000 series cards with 3-year-old firmware 6.9 that don't have an issue.
> 
> BTW, 40C is the maximum ambient temperature a "consumer" SCSI/SATA/ATA drive should be exposed to.
> Drive life dives off if they run hotter.
> So consider getting a hot-swap enlosure that fits in a  3x5.25" bay that has 5 bays.
> They run $150.
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