SSD RAIDS...

[Nick Timmons]

Buying 15,000 RPM HDD's doesn't make any sense to me, unless you bought them before SSD's prevalent.

 

[Blair S. Paulsen]

YMMV

YMMV

My goal is to create a very portable 4 SSD RAID I could travel with. ThunderBolt2 I/O, RAID controller internal to the drive enclosure. The Samsung 840 EVO 1TB drives can do >500MB/s R/W so theoretically I could get 2GB/s in RAID 0, though I'd be fine with 1,800MB/s real world - just need to be able to play out 4K/24fps Open EXR sequences in real time for 4K IIF/ACES pipelines.

Why not spinning drives? Portability mostly. Would like to be able to use it rolling down the road without issues due to bumps and vibration. This ability to move during copying is also valuable when working off a DIT cart - I can't be the only guy faced with sudden company moves, or just needing to move somewhere else on set for the reverse angle, etc. I want the ability to run on batteries or solar for hours - this also means that a small UPS could power the system for hours when paired with a rMBP - very handy when AC power is not readily available.

Fast back ups in the field!

Design parameters: <6 lbs, TB2 and USB3 I/O, 4TB (nominal) capacity, low power consumption, compact size, >1.8GB/s I/O over TB2, <$3K including the SSDs.

Call it the big data version of a USB flash drive, or the portable version of a 16 platter HDD RAID.

Cheers - #19

 

[Will Keir]

2009 this computer was brand new. I wanted the fastest drives possible. I put my faith in the Apple sales tech and he told me the fastest drives I could get would be 15,000 SAS drives with the Apple RAID card.

I was ready to do projects, so I put 10gs down on the card with 0% interest for a year and paid the extra 3g's for the 3 x 450 GB SAS drives and raid card.

I'd glad to sell them because I need the extra PCIe slot for RedRocket X.

I paid for speed, and I could have researched the drive speed and found out 4X HDDs in RAID 0 would have been just fine. That's the power of RU, knowledge, threads like this one, and people like you guys for being part of the discussion.

Buying 15,000 RPM HDD's doesn't make any sense to me, unless you bought them before SSD's prevalent.

 

[Jeff Kilgroe]

15000rpm drives do have their advantages. Their capacities are low, but seek times are faster than most 7200 and even 10K rpm drives and when paired with a reasonably good cacheing controller they can be a powerful solution for light and fast data requirements. Databases and such. Their low capacities and the fact they can't do large or streaming transfers any faster than larger drives with more platters and heads at slower RPMs makes them less valuable for the type of work we do in this business -- large video files.

I can't believe Apple ever sold that turd of a RAID card they have. So unlike them to ship such a dodgy piece of hardware. Never really fit the mold, but I guess if they were going to screw up, it was for the best with something like that than a higher profile product. And yes, I got burned by the RAID card as well. Ordered one with my '08 Mac Pro when it was launched with the system. Ugh. It hosed me several times.

 

[Will Keir]

Will it make a difference with SSD raids how large the size of the disk is?

250GB
500GB
1TB

15000rpm drives do have their advantages. Their capacities are low, but seek times are faster than most 7200 and even 10K rpm drives and when paired with a reasonably good cacheing controller they can be a powerful solution for light and fast data requirements. Databases and such. Their low capacities and the fact they can't do large or streaming transfers any faster than larger drives with more platters and heads at slower RPMs makes them less valuable for the type of work we do in this business -- large video files.

I can't believe Apple ever sold that turd of a RAID card they have. So unlike them to ship such a dodgy piece of hardware. Never really fit the mold, but I guess if they were going to screw up, it was for the best with something like that than a higher profile product. And yes, I got burned by the RAID card as well. Ordered one with my '08 Mac Pro when it was launched with the system. Ugh. It hosed me several times.

 

[Will Keir]

My current boot time with Apple RAID card (configuration: RAID 0) and 3 x 450GB 15,000 rpm drives =

1 minute 34 seconds.
1 minute 25 seconds.

Restart is 1 minute and 50 seconds.

 

[Jason Osterday]

Curious if you wound up taking the SSD route?

Also, since this thread seemed to be getting some decent action here's some numbers to throw around (or rather ponder over?):

1) 8 Drive RAID 5 (or 0) with 2.5" Drives (in a TB Expansion Chassis such as the new Magma Roben)
2) 12 Drive RAID 5 (or 0) with 2.5" Drives in same config as above using a 6 slot 5.25" bay (12 for capacity and redundancy...but is it faster than 8?)
3) TB Chassis with PCIe SSD RAID 0 Card in it (Such as the ebay brand or Sonnet Tempo)

 

[Will Keir]

I went with 2x512 Samsung 840 Pro SSDs.

Getting around 500 MB/s Read and Write. Seems like I might have done something incorrect. Speeds should be at least 600, up to 900 MB/s in theory...

 

[Jeff Kilgroe]

I went with 2x512 Samsung 840 Pro SSDs.

Getting around 500 MB/s Read and Write. Seems like I might have done something incorrect. Speeds should be at least 600, up to 900 MB/s in theory...

Hey will, saw your other thread about the RAID not working. Not sure if you have it fixed or if this post came before...

Anyway, if the SSDs are in your drive bays in the Mac Pro, then that's exactly the speed you should expect. The Mac has 3Gbps SATA connectors, which means about 250MB/s maximum throughput for each connected drive/SSD. Doesn't matter that these SSDs are a lot faster. You would get close to 700MB/s with three of them and not much higher than that if you added a fourth because the onboard SATA host has an upper ceiling of about 800MB/s in your model Mac.

 

[Will Keir]

Thanks Jeff for the clarification. I plan is to eventually put 4x drives. 800 MB/s is nothing to be upset about. 500 MB/s for that matter. Anything above the bottleneck for R3D footage. Wonder if the Dragon will need faster drives than 500 MB/s.

If I used a single 1TB SSD I should expect speeds of 250 MB/s?

So my RAID 0 isn't too bad actually. Good enough and gives me a 40 second boot, snapper program response and quicker shutdown. Plus I save some power and the RRX card uses at least 75w. Sometimes jumping my total power consumption to 400 watts which I'm a little worried about.

GTX 680
RRX Card
Caldigit USB 3 & eSATA Card
Caldigit HDONE Raid Card.

Hey will, saw your other thread about the RAID not working. Not sure if you have it fixed or if this post came before...

Anyway, if the SSDs are in your drive bays in the Mac Pro, then that's exactly the speed you should expect. The Mac has 3Gbps SATA connectors, which means about 250MB/s maximum throughput for each connected drive/SSD. Doesn't matter that these SSDs are a lot faster. You would get close to 700MB/s with three of them and not much higher than that if you added a fourth because the onboard SATA host has an upper ceiling of about 800MB/s in your model Mac.

 

[Will Keir]

Jeff,

Do you have a solid technique to building software RAID 0s in Mac OS X you could share?

Hey will, saw your other thread about the RAID not working. Not sure if you have it fixed or if this post came before...

Anyway, if the SSDs are in your drive bays in the Mac Pro, then that's exactly the speed you should expect. The Mac has 3Gbps SATA connectors, which means about 250MB/s maximum throughput for each connected drive/SSD. Doesn't matter that these SSDs are a lot faster. You would get close to 700MB/s with three of them and not much higher than that if you added a fourth because the onboard SATA host has an upper ceiling of about 800MB/s in your model Mac.

 

[Jeff Kilgroe]

Thanks Jeff for the clarification. I plan is to eventually put 4x drives. 800 MB/s is nothing to be upset about. 500 MB/s for that matter. Anything above the bottleneck for R3D footage. Wonder if the Dragon will need faster drives than 500 MB/s.

If I used a single 1TB SSD I should expect speeds of 250 MB/s?

If you are connecting to the SATA connectors that are part of the Mac Pro, then yes, 250MB/s or thereabouts for "real-world" performance. That is per device channel or internal SATA connector. They're 3Gbps connectors, which works out like this:

3,000,000,000 bps / 10 bits per byte overhead / 1048576 bytes per MB = 286.1MB/s. That is the *MAXIMUM* possible throughput on the 3Gbps SATA connectors. Combine that with typical overhead concerns and the latency of the host, among other factors, I usually just say 250MB/s. It's a bit on the conservative side, but I usually find it to be quite accurate in most real-world scenarios.

As Tim Jones pointed out around here somewhere, he's using an ATTO R680 RAID controller. It offers 6Gbps SAS/SATA connectors, which will allow for your SSDs to operate at their full potential of 500+MB/s. You could use a card like that to drive them instead of attaching direct to the integrated SATA host, get dedicated hardware RAID support and full 6Gbps per channel.

So my RAID 0 isn't too bad actually. Good enough and gives me a 40 second boot, snapper program response and quicker shutdown. Plus I save some power and the RRX card uses at least 75w. Sometimes jumping my total power consumption to 400 watts which I'm a little worried about.

GTX 680
RRX Card
Caldigit USB 3 & eSATA Card
Caldigit HDONE Raid Card.

The Mac Pro makes these sorts of things difficult. It's probably not worth it to change up what you have here just for the sake of a faster internal RAID, especially one that's going to be reasonably fast anyway if you expand to 4 devices. If you were to shake things up with a different SATA or RAID host adapter, then you would have to lose one of the cards you just listed or would have to go to some PCIe expansion and that gets expensive.

As for building software RAID sets in OSX via disk utility, there's no magic formula. I always start with totally bare drives, remove all partition data just to be sure, then just partition as needed and add drives to the RAID sets. You can play around with block sizing, but you probably don't want to stray from default on the OSX software RAIDs for most normal uses.

 

[Will Keir]

I noticed you use Windows to clear your disks. Does "Zero Out Data" in Disk Utility not do the job well?

If you are connecting to the SATA connectors that are part of the Mac Pro, then yes, 250MB/s or thereabouts for "real-world" performance. That is per device channel or internal SATA connector. They're 3Gbps connectors, which works out like this:

3,000,000,000 bps / 10 bits per byte overhead / 1048576 bytes per MB = 286.1MB/s. That is the *MAXIMUM* possible throughput on the 3Gbps SATA connectors. Combine that with typical overhead concerns and the latency of the host, among other factors, I usually just say 250MB/s. It's a bit on the conservative side, but I usually find it to be quite accurate in most real-world scenarios.

As Tim Jones pointed out around here somewhere, he's using an ATTO R680 RAID controller. It offers 6Gbps SAS/SATA connectors, which will allow for your SSDs to operate at their full potential of 500+MB/s. You could use a card like that to drive them instead of attaching direct to the integrated SATA host, get dedicated hardware RAID support and full 6Gbps per channel.



The Mac Pro makes these sorts of things difficult. It's probably not worth it to change up what you have here just for the sake of a faster internal RAID, especially one that's going to be reasonably fast anyway if you expand to 4 devices. If you were to shake things up with a different SATA or RAID host adapter, then you would have to lose one of the cards you just listed or would have to go to some PCIe expansion and that gets expensive.

As for building software RAID sets in OSX via disk utility, there's no magic formula. I always start with totally bare drives, remove all partition data just to be sure, then just partition as needed and add drives to the RAID sets. You can play around with block sizing, but you probably don't want to stray from default on the OSX software RAIDs for most normal uses.

 

[Jeff Kilgroe]

I noticed you use Windows to clear your disks. Does "Zero Out Data" in Disk Utility not do the job well?

Two completely different things. "Zero Out Data" writes zeroes to the partitioned and formatted space. This is a security and drive-checking feature.

Wiping the partition information from a utility like DiskPart (Windows), gpt (OSX) or fdisk (OSX version or windows version), is just that, it's removing the information from the header of the drive that defines partitions and how the drive is divided up. While Disk Utility (OSX) and Drive Management (Windows equivalent) are great tools, they actually can't dig into the lower levels of hard drive data structures and partition maps. Have to resort to command line tools on both systems or third-party software.

I usually do these fixes via Windows because of convenience in that the DiskPart tool is a one-stop-shop for most partition table operations.

 

[Will Keir]

Jeff,

Would you mind offering your technique when you go about creating your RAID 0 software arrays? I've never heard about "digging" into the lower levels. This somehow creates a better, more stable, faster Raid set?

Do you use bootcamp on your Mac Pros to do the windows side? How would you do a clean RAID 0 install if you were to stick with the Mac OS infrastructure?

Two completely different things. "Zero Out Data" writes zeroes to the partitioned and formatted space. This is a security and drive-checking feature.

Wiping the partition information from a utility like DiskPart (Windows), gpt (OSX) or fdisk (OSX version or windows version), is just that, it's removing the information from the header of the drive that defines partitions and how the drive is divided up. While Disk Utility (OSX) and Drive Management (Windows equivalent) are great tools, they actually can't dig into the lower levels of hard drive data structures and partition maps. Have to resort to command line tools on both systems or third-party software.

I usually do these fixes via Windows because of convenience in that the DiskPart tool is a one-stop-shop for most partition table operations.

 

[Olivier Madar]

Hi,

I dig into this thread because I am preparing my next editing computer, and the hard drive will probably be the moredifficult component to choose.

I have experimented in the past :

1) Raid 0 and Raid 5 on motherboard with Sata 7200 non serveur edition : in Raid 5, you can forget the speed, and in Raid 0 about 200Mb/sec, but i was very anxious all the time about the raid controller linked to the motherboard. It was a 18 monthes old computer with i7 processor

2) Raid 0 and 5 on a dedicated SAS PCI card (adaptec) with 4x sata 3T serveur edition on a 3960 i7 processor. This option is much much more expensive. It is my actual editing computer. Is it much better ? A little bit. In Raid 5, it is not enough (when you put a long interview in 4K HD on the timeline, you have to wait too much for the wave audio to be complete. In Raid 0, it is faster but not faster enough for editing 4 x 4KHD timeline at the same time.

3) On my editing notebook, on the other hand, I have 2 x crucial SSD 960 G and 2 x MSSD 480 G. The interesting thing is that editing is smoother when the 4K HD are on the SSD than on the Raid 0 of the "big" editing computer . Second point, MSSD are much lower speed than Crucial SSD (on Sata 6 port). Today, it seems that the Samsung 840 EVO 1T are the fastest and cheap SSD, i am looking at them more specifically.

So, What will be my next solution (in 2 or 3 monthes) ?
I am still waiting for more informations about Mac Pro and thunderbolt 2. As many of ours, i think I would like to go back to Mac IF, and only IF, the power is really here. But at this time, i think I will be stick on a windows computer...
I won't use serveur edition hard drives anymore. They are too expensive with nearly the same speed as "normal" hard drives. I will only work on SSD, and keep the hard drive for backup and archives.
I saw a 3.5 icy box for 6x 2.5 SSD that i can easily put in a computer. So, i could buy 6x Samsung 840 EVO SSD and use them in Raid with a lsi card in Raid 0 or 5 or even 6 (if the loss of speed is not too much). I don't mind a lot with speed disk test software because it does not reflect my real editiong experience. What i found the more informative today is Adobe Premiere audio wave form and moving in the timelline with project of more than 1 hour.
Of course, with 6 x SSD in raid 0 (if I can't go raid 5 or 6), I will need a very robust everyday backup process, and i should be able to switch in a few minutes my working hard drive. For that, i will use a Raid 0 external backup hard drive. I would prefer a Raid 5 backup hard drive, but it is too slow for real work. The best should be a double backup process on 2 x Raid 0 hard drive, 1 inside the computer and the other one outside.

What are your opinions ?

Olivier

 

[Kalulu Ngilo]

Just wanted to put this out here as a reference from "OffTopic" section.
http://www.reduser.net/forum/showthread.php?111611-Sales-on-scratch-drives-external-media-storage

 

[Kalulu Ngilo]

Here is a nice: Samsung 840 EVO Series 1TB 2.5" SATA III Internal Solid State Drive #MZ7TE1T0BWK -- $479.99


http://www.ebay.com/itm/Samsung-840...Internal_Hard_Disk_Drives&hash=item56609ae065

Hi,

I dig into this thread because I am preparing my next editing computer, and the hard drive will probably be the moredifficult component to choose.

I have experimented in the past :

1) Raid 0 and Raid 5 on motherboard with Sata 7200 non serveur edition : in Raid 5, you can forget the speed, and in Raid 0 about 200Mb/sec, but i was very anxious all the time about the raid controller linked to the motherboard. It was a 18 monthes old computer with i7 processor

2) Raid 0 and 5 on a dedicated SAS PCI card (adaptec) with 4x sata 3T serveur edition on a 3960 i7 processor. This option is much much more expensive. It is my actual editing computer. Is it much better ? A little bit. In Raid 5, it is not enough (when you put a long interview in 4K HD on the timeline, you have to wait too much for the wave audio to be complete. In Raid 0, it is faster but not faster enough for editing 4 x 4KHD timeline at the same time.

3) On my editing notebook, on the other hand, I have 2 x crucial SSD 960 G and 2 x MSSD 480 G. The interesting thing is that editing is smoother when the 4K HD are on the SSD than on the Raid 0 of the "big" editing computer . Second point, MSSD are much lower speed than Crucial SSD (on Sata 6 port). Today, it seems that the Samsung 840 EVO 1T are the fastest and cheap SSD, i am looking at them more specifically.

So, What will be my next solution (in 2 or 3 monthes) ?
I am still waiting for more informations about Mac Pro and thunderbolt 2. As many of ours, i think I would like to go back to Mac IF, and only IF, the power is really here. But at this time, i think I will be stick on a windows computer...
I won't use serveur edition hard drives anymore. They are too expensive with nearly the same speed as "normal" hard drives. I will only work on SSD, and keep the hard drive for backup and archives.
I saw a 3.5 icy box for 6x 2.5 SSD that i can easily put in a computer. So, i could buy 6x Samsung 840 EVO SSD and use them in Raid with a lsi card in Raid 0 or 5 or even 6 (if the loss of speed is not too much). I don't mind a lot with speed disk test software because it does not reflect my real editiong experience. What i found the more informative today is Adobe Premiere audio wave form and moving in the timelline with project of more than 1 hour.
Of course, with 6 x SSD in raid 0 (if I can't go raid 5 or 6), I will need a very robust everyday backup process, and i should be able to switch in a few minutes my working hard drive. For that, i will use a Raid 0 external backup hard drive. I would prefer a Raid 5 backup hard drive, but it is too slow for real work. The best should be a double backup process on 2 x Raid 0 hard drive, 1 inside the computer and the other one outside.

What are your opinions ?

Olivier

 

[Jeff Kilgroe]

Jeff,

Would you mind offering your technique when you go about creating your RAID 0 software arrays? I've never heard about "digging" into the lower levels. This somehow creates a better, more stable, faster Raid set?

Do you use bootcamp on your Mac Pros to do the windows side? How would you do a clean RAID 0 install if you were to stick with the Mac OS infrastructure?

There isn't a specific technique or anything like that, it's just about properly setting up hard drives, whether you use them for RAIDs or not. The majority of drives arrive from the factory in one of two forms. 1> completely unpartitioned and unformatted or bare. 2> "formatted for Windows". Essentially this means they have an MBR header on them, sometimes it also means they have a GPT/GUID header as well. They're not going to be partitioned and formatted with an HPFS file system or proper GUID partition header unless they're marketed specifically for Mac users. You occasionally see that, but typically it's just on externals marketed to Mac users.

So when I install new hard drives, the first thing I do is inspect their partitioning, if any exists. You would be surprised what can show up on hard drives sometimes. Anyway, I just wipe any of that stuff off of there and start clean, even if it's the right sort of partition header. That way it lets my system or RAID controller do what it wants to do and start the data where it wants to start. Like I said, DISKPART on Windows is very convenient for this, but you can still do the same things using the GPT, PDISK and FDISK and Disk Utility tools under OSX. I don't run boot camp on any of my Macs, I have plenty of PC's for running Windows. I have a couple eSATA drive docks that allow me to drop HDDs onto a workstation for testing and whatever, Mac or PC. The catch on the Mac is that Disk Utility will not touch any non-OSX partition, nor will it list or touch any partition flagged by an installer or manufacturer to be hidden or one that is marked as active for Windows or a few other types that are not unusual, just out of scope of the Disk Utility application.

To see what I'm talking about, load up disk utility on a newer Mac with the factory HDD or SSD installed. In Disk Utility, it will show you the drive and an associated partition. However, there's more there. If you go to the terminal window and type:

sudo diskutil list disk0

You will probably get something like this:

/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh SSD 999.7 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3

That is the internal SSD partition map on my new Mac Pro that I'm sitting at... So what we have is showing that there's a GUID partition map on a 1.0TB volume (disk0). There are three partitions -- an EFI partition used by the Mac EFI system for staging, start-up, and other tasks. The primary partition that we operate from. And the last is the recovery partition that contains key OSX install files to get the system back up and running if we wipe that main partition with all our stuff on it. Essentially, the two hidden partitions we didn't know about in Disk Utility exist so we can reboot the system in Recovery Mode and wipe our SSD and reinstall a clean OSX as if it were fresh from the factory.

You want the drives to be totally blanked out, especially if you're going to use them for RAIDs. Enterprise or RAID class hard drives will arrive new in completely blank form. Consumer drives often have other crap on them, SSDs are usually bad about this. You can use diskutil from the command line to list their partition maps and remove partition mappings. Occasionally you may find an errant drive partition or a type that diskutil won't want to delete. Then you have to branch off to other tools. From the command line in the terminal window, there is the "gpt", "fdisk" and "pdisk" tools. These can take out some stubborn partition types that diskutil may want to not touch.

You may have to unmount a disk if it's already mounted to make the changes too. You can use the graphical Disk Utility and have it open alongside your terminal window while doing this. Disk Utility can be your guide to show you what each drive is named, i.e.: disk1, disk2, etc..

Once your drives are blank of any partition mapping, you can go into disk utility (graphical one) and add them to the RAID set you're creating. The only option to choose from there is your data block size ranging from 32K up to 256K and you can check to automatically rebuild mirror sets, if you're creating a RAID-1. The block size can have an impact on performance and typically speaking the larger block size will cut down the number of transaction initiations between the system and drives and potentially increase performance. However, the down-side to large data blocks is that files always occupy some multiple of these data block sizes. For small files this can be a killer on your drive capacities as you end up with lots of wasted space.

As most of us here are media professionals, our typical files tend to be larger. Sure there's project files and XML's and PDFs and we can't get away from all the small stuff, but the bulk of our real data is larger. I would normally recommend moving up from the default small 32K block. 64K is good, 128K may be better at times on larger RAIDs. 256KB only if you're doing exclusively large files. But here's the rub... You have small SSDs making up a relatively small RAID. The SSDs are fast, nearly twice as fast as the host connection in this Mac Pro system is capable of. SSDs are also finicky on data I/O and they have their preferred block sizes in and of themselves. So on that note, it may be worth a test or two as you set up, then you can go back and rebuild and reformat the RAID with a different block size. In your situation, I think 32K or 64K is probably optimal, given all the factors. As it stands, you're only building a 1TB RAID volume at the moment...

 

[Will Keir]

Jeff, thanks for the look behind the curtain.

I don't know how to use: "fdisk" "pdisk" or "gpt." after your type:

"sudo diskutil list disk0" what are you doing next?

Disk0 refers to a single SSD in internal bay 1?
So the same command for "Disk1" will show bay 2, "Disk2" will show the drive in Internal Bay 3?

Something like this in terminal for each Internal Drive Bay.

"sudo diskutil list disk0" shows the content of Internal Drive Bay 1.
"sudo diskutil list disk1" shows the content of Internal Drive Bay 2.
"sudo diskutil list disk2" shows the content of Internal Drive Bay 3.
"sudo diskutil list disk3" shows the content of Internal Drive Bay 4.

In my case I have 2x Samsung 840 Pro SSDs in Bay 1 and Bay 2.

Typing "sudo diskutil list disk0" in terminal game me:

/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *512.1 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_HFS Untitled 511.8 GB disk0s2

Which I understand as a more detailed look at one single SSD in Bay 1.

Typing "sudo diskutil list disk1" in terminal gave me:

/dev/disk1
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *512.1 GB disk1
1: EFI 209.7 MB disk1s1
2: Apple_HFS Untitled 511.8 GB disk1s2'

Which is the same formatting I'd used for both drives and what I'd expect.

I have nothing in Bay 3 or 4. Obviously my assumption above is incorrect because typing

"sudo diskutil list disk2" gives me information about my "Lower Optical Bay" SSD with OS X and Bootcamp installed.

/dev/disk2
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *480.1 GB disk2
1: EFI 209.7 MB disk2s1
2: Apple_HFS Win7 30.0 GB disk2s2
3: Microsoft Basic Data BOOTCAMP 449.8 GB disk2s3

Looks like "disk3" is my external USB Flash Mavericks OS X Installional drive I built.

/dev/disk3
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *32.5 GB disk3
1: EFI 209.7 MB disk3s1
2: Apple_HFS OS X 10.9 Mavericks ... 32.1 GB disk3s2

and finally "disk4" could not be found.

I'll need more research or explanation how the name structure works. Especially when you get into "disk3s2"
https://developer.apple.com/library/mac/documentation/darwin/reference/manpages/man8/diskutil.8.html

This is getting more complete than my simple Disk Utility window, hehehe

You want the drives to be totally blanked out, especially if you're going to use them for RAIDs. Enterprise or RAID class hard drives will arrive new in completely blank form. Consumer drives often have other crap on them, SSDs are usually bad about this. You can use diskutil from the command line to list their partition maps and remove partition mappings. Occasionally you may find an errant drive partition or a type that diskutil won't want to delete. Then you have to branch off to other tools. From the command line in the terminal window, there is the "gpt", "fdisk" and "pdisk" tools. These can take out some stubborn partition types that diskutil may want to not touch.