Need advice w/ new internal HD

[Sco1212]

My computer:

500MHz G4(AGP)
768MB RAM
18GB 10,000 rpm Ultra/160 SCSI internal hard drive (came w/ computer)
A new 160GB internal SATA 7200rpm drive (8MB cache)
OS X 10.2.8 (I just bought 10.4 but haven't upgraded yet)


Having had enough of trying to deal with the small original HD, I bought the 160GB internal SATA drive and a PCI based SATA controller for dirt cheap and installed it but haven't transferred anything to it yet.

The simplest thing to do would be to just install 10.4 clean on the new sata drive, letting the installer transfer my files over afterward, and then just using the new drive. Given the speed of the old drive, however, (its a quantum atlas 10k, ultra160 interface), it seems a waste to do that. Are there any performance gains to be had by allocating my files to both disks (i.e. system and apps on the scsi and files on the sata drive)? I've read on other posts about designating a scratch disk area; is there any gain to be had from doing that? An even more radical idea I've had was creating a software RAID from the two drives (I know little about RAID setups, is this even possible?). I'm not sure how the drives compare performance-wise (while the SCSI is 10k, it is much older than the new drive)

I don't do a ton of video/image editing but I frequently do processor and RAM + VM intensive tasks (using Mathematica for example). Now that the college semester is over, I have the time to waste trying to eke all the performance I can get out of my system. Sorry for the longwinded post, but any advice would be greatly appreciated. Thanks

 

[zach]

The first option you suggested (allocation) is by far the best.

Transfer all your files over to your new drive and wipe the old one, then make a fresh install of Tiger on it.. and put nothing else on it.

That will DRASTICALLY improve the speed of your computer over tossing everything onto the new drive.

 

[RGunner]

need more info...

or explain it better perhaps?

the only "raptor" i know of is the WD SATA 10k Drive, which is UNBeatable, except for the newest U320 SCSI drives (big bucks).

Even a 10k SCSI can be slow, depends on model / make of the drive, the controller, the cables, the terminator.

I use a Rev 1, Cheetah 15k on a Digital Audio 800 and it FLYs, hard to compete with fast drives.

If you do have a WD Raptor, I would say reformat it and load Tiger on it, keeping other files on the second drive. You will not gain anything but headaches making a Raid boot array.

 

[Sco1212]

Sorry it is not a raptor, my mistake, it is a quantum atlas 10k, connected internally via ultra160 scsi. Given the drive's age, I wasn't sure how it would compete with the new (albeit 7200rpm) sata drive.

Also, to clarify, I should put my apps on the new drive too, putting only tiger on the older scsi drive?

 

[slooksterPSV]

That's what I'd do. Although, you can't keep all apps off your Tiger HDD, some of Apples, like iLife, have to be installed on the drive where the OS resides, why? I do not know.

 

[Sco1212]

I just tested the two drives w/ Xbench (I cloned my system to the new sata drive, used it as my boot disk and wiped the scsi drive w/ apple disk utility). The new drive across the board performed about twice as fast as the 10k scsi drive...Think it is still fastest to have Tiger on the SCSI drive?

 

[RGunner]

That would have been my guess...

Newer SATA technology, is just soo much faster...

It takes a really fast SCSI drive (new stuff) to compete with the SATA 7200 drives...

 

[Sco1212]

W/ tiger on the old scsi drive and all other files and apps on the new sata drive, xbench shows the sata drive outperforming the scsi by between 2 and 6 times on various tests, for an overall factor of about 3.5 times faster. Given this, it seems to me it might actually be faster to just have everything (including the system) on the sata drive. I'm having trouble believing I get better performance by putting tiger on the scsi drive, given how much slower it seems to be.

 

[CanadaRAM]

W/ tiger on the old scsi drive and all other files and apps on the new sata drive, xbench shows the sata drive outperforming the scsi by between 2 and 6 times on various tests, for an overall factor of about 3.5 times faster. Given this, it seems to me it might actually be faster to just have everything (including the system) on the sata drive. I'm having trouble believing I get better performance by putting tiger on the scsi drive, given how much slower it seems to be.

The problem is whether XBench's synthetic benchmarks have any relation to real life.

You want your large drive for data. A major benefit of having your scratch disk on a separate drive is that it is using a different head on a different buss.
Because operations tend to alternate continually between data and scratch space, if you separate the two, one head can be moving to the next read while the other head (in the other drive) is still completing the last one.
(this is also why most benchmarks are hopeless for evaluating real-world performance -- large sustained reads and writes are never done except in video and audio capture or copying one drive to another)

When you have scratch and data on the same drive, the head is shuttling back and forth all the time. It's like reading a book and having to continually refer to a glossary at the end. You're forever interrupting your reading to flip to the back, then flip back again to find where you left off. Now think of having the glossary on a separate reference sheet you can have open beside your book.

I would partition the 18 GB maybe 6 Gb scratch and 12 Gb System, then put the data on the SATA. The purpose to putting the Scratch on the first partition is to keep it in the fastest area of the platter (the outer tracks).

Then if you want you can partition the SATA to Active Data and Archive Data, with the active data on the first (fastest) partition again.

 

[Sco1212]

Sounds good. How do I specify that the system use the 6GB partition as a scratch disk? Also, is there any way to partition the large data drive w/o wiping it? Thanks

 

[slooksterPSV]

AFAIK, you have to redo the whole HDD if you want to partition it. When installing the OS, you click Installer->Disk Utility, from there click on the hard drive, then go to Partitions, from there specify the first Partition along with its name, and its size (I've found I always have to use the mouse slider to even change it, just typing in 6.0 won't do it for me). Anyways, after that you specify the rest as you need, be sure that you split the partitions then resize, you have to apply changes to make them stick.

 

[Sco1212]

But how will the system know to use the 6GB partitition as the scratch disk instead of using the remaining space on the partition where the system software is installed? Doesn't it treat the two partitions as if they were separate drives?

 

[slooksterPSV]

But how will the system know to use the 6GB partitition as the scratch disk instead of using the remaining space on the partition where the system software is installed? Doesn't it treat the two partitions as if they were separate drives?

If I'm thinking right, what he means by scratch, is user data.

 

[CanadaRAM]

Sorry, I jumped ahead in the discussion of scratch disks. This would be for applications like Photoshop where you can specify the location of the applications scratch disk space. AFAIK, you can't reallocate the OS scratch (Virtual Memory) space to any other than the boot volume.

If you have no programs that use their own scratch disk space, then "scratch" my prior suggestions and make the SCSI drive all one volume for the System.