[ninahagen]

I'd like to get a Mac Pro on Day 1 of the next major update.

I have already decided on 6 internal hardrives (WD 160GB Raptors) via the recently released wire harness.

One HD will clearly be the dedicated system drive.

I had originally thought of 1 HD as the scratch drive and 4 HDs in a RAID 0 array for my files.

Is this the fastest division of discs? (thinking only in terms of speed).

[tavin64]

If you only care about speed then that would be the way to go. I have 2 74gb raptors in raid 0 on my gaming pc and they fly.

[ninahagen]

I am still not clear whether to max the scratch volume to 4 disc array and just have a single disc for my files, or the complete opposite, or somewhere in between. Does anyone know the crucial factors in determining this?

[mduell]

I'd use two or three for scratch and two or three for files. And buy the hardware RAID card.

Or use one of the bays for a 1TB drive for backups; otherwise you're stuck using Firewire.

[Aegis]

Recently released wire harness? I googled and didn't find it. Could you post a link please?

[ninahagen]

Originally Posted by Aegis 

Recently released wire harness? I googled and didn't find it. Could you post a link please?

http://www.newertech.com/products/esata_cable.php

[ninahagen]

Originally Posted by mduell 

I'd use two or three for scratch and two or three for files.

I'd like to understand the reasoning behind this. Even if I take your word for it (which wouldn't be such a bad thing given the quality of your posts), I still have to decide 2+3 or 3+2, and I want to base it on which will be faster. How can I find out. If I can't figure it out beforehand I will have to configure it in all four configurations (4+1, 3+2, 2+3, 1+4) run the PS speed test, and see...

Originally Posted by mduell 

And buy the hardware RAID card.

Definitely! I wonder if I will need two cards to run two arrays or if it can be managed from one card. Is there even a place to put the second card?

Originally Posted by mduell 

Or use one of the bays for a 1TB drive for backups; otherwise you're stuck using Firewire.

Well, I figured I would just use the Supeduper (firewire 800, right?) for the backup.

[P]

You can have more than one array per RAID card, but you can only have 4 HDs connected to each card. You should also be able to partition your array in two parts.

There is space in the box for more than one card, but I'm not sure if you can order it that way from Apple.

[rehoot]

If you have a 4-disk RAID 0, it would be silly to use a single disk as scratch. Use the fastest stripe that you have. Also, if you boot from a single disk, delete the ~/Library/Caches file and replace it with a link to the 4-disk RAID 0. From Terminal:

mkdir /Volumes/MyRAIDVolume/Caches
sudo ln -s /Volumes/MyRAIDVolume/Caches ~/Library/Caches

You can consider using a similar trick to alter the /tmp directory, but to make the change you might have to boot from another volume to avoid difficulty with the directory being in use. You can format the RAID 0 so that you can use it as an emergency boot volume.

Other options would be to put all the drives in a single RAID 0. The only time that you would have a problem is if there is a firmware update, in which case you would need an additional disk that you could pop into the Mac Pro, boot from it, and apply the firmware change, then reinstall the old array.

I have a 150GB Raptor boot drive and a 3-disk RAID 0. My previous config was a 2-disk RAID 1 for boot and a 2-disk RAID 0 for scratch and files (with a firewire backup). I split my 3-disk RAID 0 into partitions with one partition acting as an emergency boot volume/clone of my boot drive and the other for video.

I recently bough a Western Digital Caviar SE 16, 500GB, and I must say that it is pretty fast. If you need space for video or other such things, the Caviar is also a good choice.

If you need storage space, you might want to try a 2-disk RAID0 of 500GB drives for boot.

As for the RAID card, that would be good if you wanted RAID 5, but it sounds like you don't need that. I'm guessing that in your case, you would need a card only if you want to create an 8-disk RAID 0 in an external bay (or mixed internal and external). This would be expensive, and the reviews that I read suggest that there is a moderate chance of random problems associated with the cards.

If you put 6 Raptors in your Mac Pro, I hope you have good ventilation. They run hot.

[rehoot]

Originally Posted by P 

There is space in the box for more than one card, but I'm not sure if you can order it that way from Apple.

Check the specs on the cards before you buy them. If the card does not say that it will function when there is a second card, then don't assume that it will do so. I can't find the link right now, but one of the cards I was researching recently said that you can use only one per machine.

Here is a link to some good RAID reviews:
http://www.amug.org/amug-web/html/am...s/reviews.html

[ninahagen]

First, I just want to say thanks for the help with this complex issue.

Originally Posted by rehoot 

If you have a 4-disk RAID 0, it would be silly to use a single disk as scratch. Use the fastest stripe that you have.

I had no idea that was even possible. How do you designate a stripe for exclusive use as the scratch disc? Also, just one stripe? And how can I know which stripe is fastest?

Originally Posted by rehoot 

Also, if you boot from a single disk, delete the ~/Library/Caches file and replace it with a link to the 4-disk RAID 0. From Terminal:

mkdir /Volumes/MyRAIDVolume/Caches
sudo ln -s /Volumes/MyRAIDVolume/Caches ~/Library/Caches

How will that speed things up?

Originally Posted by rehoot 

You can consider using a similar trick to alter the /tmp directory, but to make the change you might have to boot from another volume to avoid difficulty with the directory being in use. You can format the RAID 0 so that you can use it as an emergency boot volume.

Sounds dangerous.

Originally Posted by rehoot 

Other options would be to put all the drives in a single RAID 0.

I am nervous about putting the system drive into the RAID array, especially since I may partion the system drive to run windows for games.

Originally Posted by rehoot 

I have a 150GB Raptor boot drive and a 3-disk RAID 0.
My previous config was a 2-disk RAID 1 for boot and a 2-disk RAID 0 for scratch and files.

Which configuration is faster?

Originally Posted by rehoot 

I recently bough a Western Digital Caviar SE 16, 500GB, and I must say that it is pretty fast. If you need space for video or other such things, the Caviar is also a good choice.

Yes, I have heard and read the specs on the caviar. Still it is a compromise. I would rather make the compromise of a firewire 800 backup. I figure 4-5 Raptors = 640~800GB of internal storage space... after a closer look that seems it will be enough, and the Superduper can hold all that. I believe it will also hold the contents system drive so I can boot from it if my system drive fails. This brings up something else I hadn't thought of which favors a separate scratch drive. If the RAID array should fail, while I am waiting for replacements/repairs I can export files I want to work on from the Superduper to scratch disc, which probably would not have failed at the same time. So I would still be up and running.

Originally Posted by rehoot 

As for the RAID card, that would be good if you wanted RAID 5, but it sounds like you don't need that. I'm guessing that in your case, you would need a card only if you want to create an 8-disk RAID 0 in an external bay (or mixed internal and external). This would be expensive, and the reviews that I read suggest that there is a moderate chance of random problems associated with the cards.

Are you saying I should use a software RAID?

Originally Posted by rehoot 

If you put 6 Raptors in your Mac Pro, I hope you have good ventilation. They run hot.

That does worry me a bit. Will have to install an dedicated a/c in the ofice that houses the beast. Thanks for reminding me.

[edge.it]

1 system
2,3 raid 0 - scratch
4 windows
5 data
6 data

you should get an external enclosure for the other drives.

[mduell]

Originally Posted by P 

You can have more than one array per RAID card, but you can only have 4 HDs connected to each card. You should also be able to partition your array in two parts.

There is space in the box for more than one card, but I'm not sure if you can order it that way from Apple.

Nonsense, the hard drives don't connect to the card. The card works with the SATA ports already on the logic board. This is pretty common in the workstation/server market.

Originally Posted by ninahagen 

I'd like to understand the reasoning behind this. Even if I take your word for it (which wouldn't be such a bad thing given the quality of your posts), I still have to decide 2+3 or 3+2, and I want to base it on which will be faster. How can I find out. If I can't figure it out beforehand I will have to configure it in all four configurations (4+1, 3+2, 2+3, 1+4) run the PS speed test, and see...

Definitely! I wonder if I will need two cards to run two arrays or if it can be managed from one card. Is there even a place to put the second card?

Well, I figured I would just use the Supeduper (firewire 800, right?) for the backup.

You'd have to benchmark your workflow (not just some PS speed test) on the different configurations to tell. Using 2-3 for each instead of 4 and 1 is just a gut feeling.

You don't need two cards.

You could run Superduper no matter what bus you're using to connect the drives. Given the cost and performance of FW800 enclosures, I don't see them being a good value compared to using one of your eSATA disks for backup.

[rehoot]

Originally Posted by ninahagen 

I had no idea that was even possible. How do you designate a stripe for exclusive use as the scratch disc? Also, just one stripe? And how can I know which stripe is fastest?

In the Mac Pro, which has independent "data pathways" to each drive, a 2-disk stipe is almost twice as fast as one disk (assuming that both dists are the same model). A 3-disk RIAD 0 is almost three times as fast as on disk (may 2.5+ times faster depending on the file size).

The idea of having a separate scratch volume might come from the idea that you want a more stable drive for your main work. For example, a single drive is more stable than a RAID 0 because the RAID will fail if any single drive fails--and peoploe want to avoid the higher risk of losing their main files. If you are in dire need for speed, then you don't need a separate RAID 0 for scratch--especially if you are going to store many files on a RAID 0 any way. If you wanted the security of RAID 1 for your main files, then it would make sense to have a separate RAID 0 exclusively for scratch (I'm guessing that this does not apply to you).

There is one other potential advantage for using one RAID 0 for scratch and files (as long as you have a good backup system)--that is that some programs write to the scratch disk for temporary files and then rename them to make them real. If scratch and files are on separate volumes, then that file has to be copied instead of simply being renamed. This varies according to each program.

Making the RAID the "exclusive" scratch disk would involve the ln -s ... command suggested above (for the Caches folder and the /tmp folder), plus checking each major program that you use to see if there is a separate option for using a scratch folder. I have not altered my /tmp folder, so maybe search this forum to see if there are other tips from people who have done it.

Originally Posted by ninahagen 

I am nervous about putting the system drive into the RAID array, especially since I may partion the system drive to run windows for games.

That's fine. I no longer boot from a RAID.

Originally Posted by ninahagen 

Which configuration is faster?

The fastest configuration without going to RAID cards or external drives would be a 4-disk (or 6-disk if squeeze extra drives into the Mac Pro) RAID 0 (booting from that RAID). The second fastest would be to boot from a Raptor and run a RAID 0 on the remaining drives (as long as you have a good backup of everything--backup up the modified files every couple hours when working on really important things).

Originally Posted by ninahagen 

If the RAID array should fail, while I am waiting for replacements/repairs I can export files I want to work on from the Superduper

Yes, that's a good plan

Originally Posted by ninahagen 

Are you saying I should use a software RAID?

Assuming that you will buy the same disks regardless of your choice of software or hardware RIAD, why not try software RAID first before you spend the extra money? PLUS if you are doing RAID 0, there is extremely little difference in speed between a software RAID 0 on Mac Pro and a hardware RAID 0 that uses the same number of disks.

If you think you need an 8-drive RAID 0, then obviously you need to get a RAID card and go external. After you test all your software RAID options, you can make that decision

Originally Posted by ninahagen 

That does worry me a bit. Will have to install an dedicated a/c in the ofice that houses the beast. Thanks for reminding me.

The recommended max air temperature for a Mac Pro with normal configuration is 95 degree farenheit. If the temperature in the room is above 85, you might want to put some regular fans (as in a 10-inch fan that sits on the floor) near the computer to be sure that there isn't an area of dead, hot air surrounding your computer. Before you laugh at this, I had heat problems with a PowerBook, and they were solved by putting a fan next to my computer to help dissipate the heat.

I live in a hot environment and avoid using the air conditioner. I generally avoid using the computer if the air temperature is over 90 (which is mighty hot for indoors)--or I'll use the air conditioner if I really need to work on the computer.

[ninahagen]

I'm humbled. What a blazing great post! Thanks ever so much for putting the time and thought into this.

I'm into the idea of skipping the dedicated scratch disc. Some issues:

- Can stripes really be designated withinin CS3 as the scratch "disc" instead of an actual HD? If so, how is that done? Or do you mean that whole copying to scratch process becomes moot or eclipsed in the face of so much speed and the command modifications you suggest?

- With the Superduper in the background, I feel safe running RAID 0 for files and scratch functions. I think I will give up the 6th disc in the array, so that if one disc and consequently the whole array fails, at least I will have the system drive, which at 160 GB will hold enough files from the Superduper to at least function. How much speed will I lose? If a 5 disc array would be say 4.5 times faster than a single disc and a 6 disc array would be 5.4 times faster, then about 20%? slower. I am I thinking correctly about the Superduper? I mean, if I could boot from it in case of a failed array, and do all my work at Firewire 800 speed until the array is fixed, why not just go for a 6 disc array and and put the system and software on there as well? (in this case I would just skip windows... I don't do much gaming).

Originally Posted by rehoot 

I no longer boot from a RAID.

For the same reasons as I outlined?

Originally Posted by rehoot 

Assuming that you will buy the same disks regardless of your choice of software or hardware RIAD, why not try software RAID first before you spend the extra money?

I will be buying 6 Raptors or whatever their fastest drive is at the time the Leopard & the new MP are out. I think I will try the software RAID first, as long as Apple is offering the card as an add on... now it seems you have to order it with the computer.

Originally Posted by rehoot 

PLUS if you are doing RAID 0, there is extremely little difference in speed between a software RAID 0 on Mac Pro and a hardware RAID 0 that uses the same number of disks.

I didn't know that RAID 0 was nearly the same speed in both software and hardware RAID. Are you certain of this? Could you explain some of the reasoning for that? If it is a 1% difference, then I will just skip it. But a 10% difference would cause me to spring for the card.

Originally Posted by rehoot 

The recommended max air temperature for a Mac Pro with normal configuration is 95 degree farenheit. If the temperature in the room is above 85, you might want to put some regular fans (as in a 10-inch fan that sits on the floor) near the computer to be sure that there isn't an area of dead, hot air surrounding your computer. Before you laugh at this, I had heat problems with a PowerBook, and they were solved by putting a fan next to my computer to help dissipate the heat.

No laughing! I agree and take this seriously.

[rehoot]

I don't have CS3, but the new menu options are shown here for scratch disk:

Photoshop CS3 Essential Preference Settings Page 3 - Free Adobe Photoshop Tutorial

You can't boot from a firewire 800 drive as far as I know. You can boot from an external drive if you have an eSATA or FiberChannel card. Having a single boot drive would be a bit safer and more convenient that putting all your disks in a single RAID 0.

There is one thing about 6 drives that might be in question. I don't know if the CD/DVD bays share the same channel or if there are two channels. If they share a channel, then putting two drives in it might not be quite as fast as it would be if they were on separate channels. If you find that adding the 6th drive does not add any benefit, you can either keep the drive as a spare or add it as a stand-alone volume for backups. There might be no noticeable impact, but it's something to keep in the back of your head while testing.

My "guesstimate" of a 4-drive RAID 0 being 3.5 times faster than a single disk is just a guesstimate. It will vary depending on factors like block size and file size and who knows what else. I don't have any benchmarks handy for my current config, but here are some (consider disk type and number of disks when comparing):

software RAID example (search for Four Drive Striped ) :
AMUG Apple Mac Pro 2.66 GHz Review

hardware RAID example (might be different disks)
AMUG DAT Optic eSATA_PCIe8 4 port PCI-e 8x SATA PM Host Adapter Review
Highpoint RocketRAID 2322 PCI Express SATA II host adapter
RAID 5 versus RAID 0 on G5 Power Mac (RocketRAID 2220)

[P]

Originally Posted by mduell 

Nonsense, the hard drives don't connect to the card. The card works with the SATA ports already on the logic board. This is pretty common in the workstation/server market.

The spec for the card still says that 4 drives is the max that it will handle for RAID 0. Linking into the Applestore only sorta works, but you can go there yourself and click Mac Pro -> Configure -> Learn more about the RAID card. The text you get is this:

The Mac Pro RAID card offers improved performance and data protection to your Mac Pro system — up to 304MB/s of sequential read performance in RAID 0. Ideal for video and creative professionals with demanding storage needs as well as for tower server applications, this hardware RAID option supports RAID levels 0, 1, 5, 0+1, and Enhanced JBOD. It has 256MB of cache and an integrated 72-hour battery for protecting the RAID cache. The card occupies the top PCI Express slot (slot 4) and connects to the four internal drive bays.

To enable your Mac Pro for hardware RAID, select the Mac Pro RAID card option and two or more hard drives in bays 1 through 4. Each RAID level has minimum requirements for the number of hard drives:
RAID Level Drive Requirements Benefit
Enhanced JBOD One to four drives A non-RAID configuration with the ability to migrate to a RAID set at any time
RAID 0 (striping) Two to four hard drives Maximum performance and capacity for the most demanding I/O requirements
RAID 1 (mirroring) Two hard drives Maximum protection for critical data
RAID 5 Three or four hard drives Data protection, up to 199MB/s of sequential read performance, and efficient capacity utilization
RAID 0+1 Four hard drives A mirror of striped drive pairs providing performance and data protection

The Mac Pro RAID card supports the creation of multiple RAID sets in a system and multiple volumes per RAID set. For optimal disk utilization in a RAID set, all hard drives should be the same size. Your Mac Pro system ships with each hard drive individually configured in the Enhanced JBOD level with Mac OS X installed on the drive in bay 1. Using Apple's RAID Utility software, you can migrate the drives into a RAID set without reinstalling Mac OS X or reformatting the drives, or you can customize your RAID volumes to meet your exact requirements.

Please note: The Mac Pro RAID card occupies one of the available PCI Express expansion slots.

[ninahagen]

Thanks P & Rehoot!

Rehoot, could you take the Photoshop speed test and let me know your results?

http://www.retouchartists.com/pages/speedtest.html???