newworld g3/g4 - internal boot from SCSI - any speed benefit over IDE?

[supernova777]

has anyone here got experience using a SCSI hd on a b+w g3 or sawtooth?

for me personally ive seen tons of benefit using bootable SATA pci card adapters on these machines

but i've never actually used a real internal SCSI hd connected to a SCSI pci card.. like an adaptec

is there any speed/performance increase over the built-in IDE when doing such a configuration?

or is it basically the same as IDE.. and not worth the effort to setup

 

[Elfen]

Unless you are using high end 100K RPM Baracuda (Server) SCSI Hard Drives, there is no speed advantage. PATA/IDE, SATA, SCSI, are all the same (to me) and it depends on the RPMs the drives is spinning that makes or breaks the system.

Yes, SATA has a 3.0 to 9.0(?) GB/sec data transfers but if you have a slow drive on the system, it will not matter how fast your interface is you are not going to see any gains in speed on the system.

The fastest PATA is around 200MB/sec (or a bit more) but having a fast drive on that can beat a SATA with a slow drive. So go figure.

The same is true with the SCSI (and Serial SCSI - used on the old Intel XServes).

If you want a fast system, in the least you should have fast drives. As a minimum - 7200 RPM Hard drives and not 5600 or 4400 RPM hard drives. If you want really fast - consider an SSD with a fast hard drive hack up.

 

[supernova777]

thanks for sharing your insight Elfen!

 

[Elfen]

The fastest drive out there is a RAM Drive.

HyperOS has one that connects to SATA Port, and can have up to 48GB (due to 8GB DDR2 RAM and having 6 slots for it). Its about $400 for an empty drive (you buy and put in your own RAM). http://www.hyperossystems.co.uk/07042003/products.htm

Faster still were the PCI/PCIe RAM Drive cards as they connect directly to the system's Bus and ties into the OS through the CPU (depending on your PCi interface). There were many companies that made these, including Dell and HP for server applications. But they were/are very expensive. One such product is this:

http://www.thessdreview.com/our-reviews/allone-cloud-disk-drive-101-ramdisk-review-500k-iops-ddr3-storage/

The problems with RAM drive systems is that they are made of RAM. 1) without a battery or some other form of back up, when power goes down you lose your data. 2) in case of a virus, with a hard drive files are slowly infected over time; with a RAM drive - one file gets infected, they all get infected instantly - this is due to the speed of the media accessing the files - nothing beats RAM.

Another issue is Mac Compatibility. Many of these PCI RAM Drives will not work on a Mac. The SATA and PATA ones are compatible because they can connect to the Mac's hard drive interface.

 

[Cory5412]

If you got a 10k or 15k drive and connected it to a good Ultra160 or Ultra320 controller, it would be faster than IDE, hands down. The fastest IDE controllers were 133 megabits per second, but I don't know how many disks ever shipped at 133 spec, because by then, SATA was coming down the pipe.

Original SATA is 150 megabits per second, followed by SATA 2 at 3.0 gigabits per second and SATA 3 at 6.0 gigabits per second.

At the end of the day: You're going to get a performance boost in a Power Macintosh by putting in a third party disk controller card and a faster disk. What type of disk you use is up to your needs and budget.

For reference, the Power Macintosh G4 ("AGP Graphics" or "Sawtooth") had ATA/66, and the Blue-and-White Power Macintosh G4 and the Power Macintosh G4 ("PCI Graphics" or "Yikes!") had ATA/33.

Back in the day, there was no real functional limitation on that ATA/33 controller in a Yikes! G4 (even using slave drives!). It captured DV video with no troubles, and so the only real reason to put anything faster in is if you need bigger, you just want it, or you're using analog video or high definition video capture hardware, which needs a higher bit rate than DV video. This was all true even on Mac OS X.

Thinking about RAM disks: I'm sure you could do a little better now, but modern SSDs such as the Intel 750 are almost to the point of doing 500,000 IOPS without needing to involve RAM.

What are you doing with the system? If it's just generally for poking around and your hard disks aren't dying, you aren't missing much from the "slow" storage in that machine. The G4 era was when Macs stopped getting a whole lot faster year over year and when they started losing out in terms of raw performance compared to literally everything else in the industry -- not just compared to slightly more expensive UNIX workstations.

If your system's slow and you already have max RAM, it's more likely because it's a slow system, and not something one cheap component can fix.

SSD upgrades are nice anyway though. It should make launching apps faster, but it won't do anything for things like web page rendering times or video/photo workflows that are CPU bound (on a G4: all of them.)

 

[supernova777]

What are you doing with the system? If it's just generally for poking around and your hard disks aren't dying, you aren't missing much from the "slow" storage in that machine. The G4 era was when Macs stopped getting a whole lot faster year over year and when they started losing out in terms of raw performance compared to literally everything else in the industry -- not just compared to slightly more expensive UNIX workstations.

If your system's slow and you already have max RAM, it's more likely because it's a slow system, and not something one cheap component can fix.

SSD upgrades are nice anyway though. It should make launching apps faster, but it won't do anything for things like web page rendering times or video/photo workflows that are CPU bound (on a G4: all of them.)

there was no specific system in mind, my comment stemmed from the fact that i have tons of experience using SATA drives in G4's (to great effect) but little to none experience doing the same with a SCSI card + physical SCSI drive.

re; SSD's i think they are wasted on a g4... the seek times are definately the biggest + because the bandwidth is limited to sata1 due to the adapters, actually i think theres one sata2 adapter for osx only, but u can get mechanical sata3 spec drives that perform similarly for half the cost of an SSD.. well that USED to be the case in 2012/13/14 ... perhaps now in 16 the SSD prices have come down? but i doubt u can get an 80GB ssd for 20$ the way i scored bunch of 80GB drives for 20$ a pop not long ago.

anyways.. like i said. im very familiar with all the speed ratings.. im just totally inexperienced with SCSI, and i  was talking to someone who was asking for my help to put together a 1999-2000 g4 mac, for playing around with os9 + audio apps... for SCSI transfers to hardware samplers.. and he mentioned he also has a scsi drive and he asked me if it would be good to run the system off the scsi drive rather then the built in ATA.

 

[Bunsen]

IMO if he is looking at those two choices and he already has them both in front of him, booting and running the system from SCSI is probably the better of the two.

 

[supernova777]

i also remember that the b+w g3 "SERVER" systems we had at the place i worked at in 1999 i think came configured with SCSI cards + SCSI drives.. 

that was floating around in my mind when i made this post although i never wrote it in my post.

 

[johnklos]

With UNIX, and therefore Mac OS X, disk I/O through a card that supports real DMA creates less overhead than through an interface or card that requires the CPU to do lots of work.

Older m68k Macs had the processor do all the work with their SCSI. Newer m68k Macs had pseudo-DMA - they'd DMA small chunks and the processor would still have to do lots of work. This didn't matter because the OS couldn't do anything else while the I/O was occurring. When Apple started getting a little more serious about A/UX, though, they included a PDS card in the Workgroup Server 95 which had SCSI with real DMA so A/UX could do other things with the CPU while disk I/O was happening.

This was also very apparent when I ran Mac OS on my Amiga - the SCSI controller I had was excellent at DMA, so when Mac OS would be doing heavy disk I/O, the CPU would be nearly completely free for Amiga programs.

For G3 and early G4 systems running Mac OS X, a real DMA bus might have noticeably less overhead than IDE, but by the time later G4s came around, the speed of both the bus and the computer made this mostly irrelevant.

Think of it this way - even if an IDE bus causes the CPU to spend 100% of its time doing a transfer, if you have a drive which can do 50 MB/sec on an IDE bus which is running at 100 MB/sec, utilizing the disk completely could never take more than half of the CPU's time. In reality, IDE started getting a kind of DMA (not real DMA since it still required a bit of hand-holding) that made it able to transfer at high speeds with less overhead, so when transferring 50 MB/sec with IDE only imposes 10% CPU overhead, it's not worthwhile to pay all that extra money for a SCSI controller and SCSI drives to be able to do 50 MB/sec with less than 5% overhead.

There are times when it matters. The SCSI controller support in NetBSD is very mature, so my Power Mac 9600 server has an 80 MB/sec ATTO SCSI card with 2 TB hardware mirrored SATA on a SATA-SCSI adapter. Could I have just used a SATA card? Sure, I could've. But considering how slow the busses are in a 9600, reducing overhead by using SCSI made more sense.

 

[Cory5412]

I just reread the original post.

Going just by what was available in 1999 when these systems were on sale: Yes, there was a speed benefit to SCSI if you put a bunch of money into a good controller and one or more good disks.

This is both because Ultra-3/160MB scsi was introduced at the tail end of 1999, and for the DMA issues commodorejohn mentions. (Although, I think IDE was completely DMA ready by the time 1999 rolled around, I'd need to go research it.)

If SATA is available, there's literally no good reason to bother with SCSI at all unless you happen to have all the equipment around, or you need at least one SCSI interface for some "legacy" reason (such as data transfer with a synth, for example.)

SSDs will make a huge difference even on seek time alone, but an interesting thing is, most spinning disks don't even max SATA 2 (3 gigabits) so if you need big sustained transfer speeds (unlikely on a PPC Mac, though) then SSD is the way to go as well, because you're going to get better sustained transfer speeds in addition to the reads and writes.

Of course, this all depends on the specific data you're working with and these days, fewer and fewer things are happening in real time, and video production has almost completely eliminated realtime.

That said, the built in IDE is probably going to be fast enough on those systems -- I did plenty of DV video capture on those systems with no trouble. The key is using a separate disk, ideally on its own controller, but it can be the slave disk if need be, and keeping the disk free of fragmentation.

Audio only may be slightly different though.

There are times when it matters. The SCSI controller support in NetBSD is very mature, so my Power Mac 9600 server has an 80 MB/sec ATTO SCSI card with 2 TB hardware mirrored SATA on a SATA-SCSI adapter. Could I have just used a SATA card? Sure, I could've. But considering how slow the busses are in a 9600, reducing overhead by using SCSI made more sense.

Does NetBSD not treat SATA like SCSI? Everything else does, including Mac OS 7/8/9, as far as I've seen.

Though, if you have a SCSI card or you have a system where you can't easily a SATA card, an adapter like that sounds like a good idea. Do you have a link to the one you used?

 

[IPalindromeI]

You'd think NetBSD would have mature support for SATA adapters. I'd trust it more than another thing in between the HD and the buses.

 

[johnklos]

NetBSD does have mature support for SATA adapters, but when I put this SCSI card in the Power Mac in 2004, SATA was still pretty new and the chips were still a bit buggy. The Silicon Image chips which were quite common then had more than a few errata which had to be worked around in software.

NetBSD doesn't distinguish between disk busses except for having different device names (sd, wd, ld). The underlying hardware determines the amount of overhead, not how the OS treats the disks. A typical SCSI controller, even many older ones, can DMA 16 megabyte blocks at one time, for instance, whereas an early SATA controller or older IDE controllers may only do a handful of blocks (16 or 32) per interrupt. Some IDE interfaces used third party DMA, which also made the system do work.

For modern IDE (like mirrored drive door G4s) and SATA, the overhead is now insignificant compared with SCSI.

 

[Unknown_K]

It depends on a few things mostly, how much money you want to blow.

Are there any PCI-X SATA cards for the mac? PCI is rated for 133MB/sec max and you know Apple never made drivers that would allow anywhere near that plus other things use that BUS.

Newer SATA drives on a PCI-X card would be the fastest single drive option, and also expensive. You might be stuck with OSX.

There are a number of SCSI 160/320 options for PCI-X and if external drives are an option you can get something like a Medea Videoarray full of IDE or SATA drives raided to SCSI interface that kick ass.

The SATA or SCSI options also get rid of the drive size issues using the native ATA interface of pre second generation Quicksilver machines (128GB Max).

 

[supernova777]

yes there are pcix sata cards for mac...

and i own them

i know sata is the best..

i was asking if SCSI > IDE

or if IDE == SCSI 

 

[Bunsen]

Answered above.