SSD Drives for Mac Pro Boot Drive?

[NoManIsland]

Hello Nanofrog,

Sorry for the double post - I made the new thread first, but it got no hits for a long time, then I noticed this thread would be appropriate

I would really like to use the Pro Drive as my boot drive with a couple Intel X25-V's. I have two Seagate Barracuda 1TB drives (11th gen), and I'm buying a WD Black 2TB drive today. The idea will be to put the two Seagates in software RAID 0 for data, have the WD as Time Machine (eventually to be replaced with two externals for onsite and offsite backup), and have the two SSDs in RAID 1 in the Pro Drive so I can avoid downtime due to a failure. Do you think this arrangement will bottleneck? And would putting the two SSDs in RAID 0 instead be a huge waste?

 

[nanofrog]

Hello Nanofrog,

Sorry for the double post - I made the new thread first, but it got no hits for a long time, then I noticed this thread would be appropriate

I would really like to use the Pro Drive as my boot drive with a couple Intel X25-V's. I have two Seagate Barracuda 1TB drives (11th gen), and I'm buying a WD Black 2TB drive today. The idea will be to put the two Seagates in software RAID 0 for data, have the WD as Time Machine (eventually to be replaced with two externals for onsite and offsite backup), and have the two SSDs in RAID 1 in the Pro Drive so I can avoid downtime due to a failure. Do you think this arrangement will bottleneck? And would putting the two SSDs in RAID 0 instead be a huge waste?

Given the fact the X25-V's can only do ~180MB/S, and you're going for RAID 1, you should be fine (no bottleneck on the ICH, as you'd be under 500MB/s, and the ICH won't hit the wall until ~660MB/s).

I'm just not sure of the latency introduced from the PM chip with SSD's. You could put one in HDD bay one, and the other in the empty optical bay, giving them each their own SATA port. This would eliminate the need for the Pro Drive, and is cheaper (using at least 1x of the SSD's in Retail form for the included adapter). You can get a cheap 3rd party mount for the optical bay (3x 2.5" to 1x 5.25" Rafter, and last I looked is ~$7 USD here; it's just plastic).

Just a thought.

 

[NoManIsland]

Given the fact the X25-V's can only do ~180MB/S, and you're going for RAID 1, you should be fine (no bottleneck on the ICH, as you'd be under 500MB/s, and the ICH won't hit the wall until ~660MB/s).

I'm just not sure of the latency introduced from the PM chip with SSD's. You could put one in HDD bay one, and the other in the empty optical bay, giving them each their own SATA port. This would eliminate the need for the Pro Drive, and is cheaper (using at least 1x of the SSD's in Retail form for the included adapter). You can get a cheap 3rd party mount for the optical bay (3x 2.5" to 1x 5.25" Rafter, and last I looked is ~$7 USD here; it's just plastic).

Just a thought.

Thanks for the analysis. I realize the limitations of the Pro Drive, but I'm inexplicably drawn to it I like the idea of the drives being neatly packaged together in a drive bay, easily accesible, and leaving the ODD bay for either a Blue-Ray drive later on, or perhaps a Pro Caddy 2 or the like when storage demands it. I realize that the Pro Drive isn't the most cost-effective or ideal solution performance-wise, I just kind of love it anyways But you would definitely say that a RAID 0 in the Pro Drive would be uselessly bottlenecked?

 

[NoManIsland]

How much would the port multiplier in the Pro Drive restrict a RAID 0 set of X25-Vs? If it over-saturates it, but the actual choked performance is close to the normal performance on two separate SATA ports, I'd probably still consider doing it. How much of a performance boost would striping the two SSDs in the Pro Drive have compared to the RAID 1 configuration?

 

[NoManIsland]

Nano, does this math make sense? If the X25-Vs run at a max of 180 MB/s, but they are splitting a SATA port's bandwidth, they would be running effectively at 150 MB/s, so a RAID 0 of them would hit the SATA maximum of 300 MB/s? This compares to them being on separate ports at 180 + 180 MB/s = 360 MB/s, so I'm only losing 60 MB/s by using the Pro Drive? To me this would be acceptable as I could then mount 2 3.5" HDDs in the lower ODD bay using the two extra SATA ports, plus the X25-Vs aren't going to be hitting their max all the time, so the bottleneck is perhaps less significant then it would seem. Let me know if this checks out.

 

[nanofrog]

But you would definitely say that a RAID 0 in the Pro Drive would be uselessly bottlenecked?

Absolutely.

The max throughput is 200MB/s with that device no matter the RAID level used. As a 2x disk X25-V would be capable of ~360MB/s (reads), you'd be loosing nearly half of the real potential. So it would definitely bottleneck on you.

That's why with a stripe set (RAID 0), you need to have 1x SATA port per drive with SSD (and some of the newer drives do give better throughputs on 6.0Gb/s SATA than 3.0Gb/s SATA, even though the throughput of the drive is less than what 3.0Gb/s saturates at (realistic value, which happens to be
~270MB/s, not theoretical = 375MB/s). Double that for 6.0 Gb/s spec.

How much would the port multiplier in the Pro Drive restrict a RAID 0 set of X25-Vs? If it over-saturates it, but the actual choked performance is close to the normal performance on two separate SATA ports, I'd probably still consider doing it. How much of a performance boost would striping the two SSDs in the Pro Drive have compared to the RAID 1 configuration?

You'd hit the wall at 200MB/s, so you'd loose 160MB/s using the Pro Drive for a stripe set. It's better suited to RAID 1 with SSD's.

The Pro Drive would be fine for mechanical drives (what the PM chip was designed for).

Nano, does this math make sense? If the X25-Vs run at a max of 180 MB/s, but they are splitting a SATA port's bandwidth, they would be running effectively at 150 MB/s, so a RAID 0 of them would hit the SATA maximum of 300 MB/s? This compares to them being on separate ports at 180 + 180 MB/s = 360 MB/s, so I'm only losing 60 MB/s by using the Pro Drive? To me this would be acceptable as I could then mount 2 3.5" HDDs in the lower ODD bay using the two extra SATA ports, plus the X25-Vs aren't going to be hitting their max all the time, so the bottleneck is perhaps less significant then it would seem. Let me know if this checks out.

No, the math is wrong.

Stripe set Throughput:
Throughput of set = n drives * (throughput of single drive)

So 2x X25-V = 2 * 180MB/s = 360MB/s

But the speed will be bottle necked by the PM chip in the Pro Drive. They claim it's 200MB/s (spec; only has 2x drives rather than 5x max that other PM chips can handle, and the additional drives only push throughput's to 250MB/s).

Hope this clears things up for you.

 

[NoManIsland]

Thanks Nano - it's not the answer I was hoping for, but it's good to know the limitations

 

[nanofrog]

Thanks Nano - it's not the answer I was hoping for, but it's good to know the limitations

Sorry it's not what you were hoping for, but better to know now than later and deal with returns or disappointment.

I'm glad though to see you're putting the time in to research this before leaping prematurely.

 

[NoManIsland]

If anything I tend to over-research Drives my wife mad as I tend to blather on and she has about as much interest and aptitude in computers as I have in square dancing

 

[smarty-s]

sorry but i need help.....

Hi together

I see here are the really macfreaks .....

I posted from Germany ( as well my Englisch is not verry well ... )

But in Germany no one can help me ....

I have a MacPro ( 2x2,26 8 core Nehalem ) late 2009 an i buy 2x crucial 256GB SSDs . one of the best on the market ....

every SSD formated with MacOSX Journaled and with one Partion GUID ...

every ssd runs 220mB/s Read 100mB/s write. benchtest with AJA

Now I build a softwareraid with the two ssds but now the speed is 80 read 60 write !!!!

for two day ist works verry well ( 350 read 200 write ) but now the speed is to slow

now my question :

1) What can be the source of the problem ?

2) need i any Raid Card ?? and if you say yes i need one what kind of card i can use it - the original from apple or any other labels ???

Best regard from the cold Germany !

smarty-s

 

[nanofrog]

Hi together

I see here are the really macfreaks .....

I posted from Germany ( as well my Englisch is not verry well ... )

But in Germany no one can help me ....

I have a MacPro ( 2x2,26 8 core Nehalem ) late 2009 an i buy 2x crucial 256GB SSDs . one of the best on the market ....

every SSD formated with MacOSX Journaled and with one Partion GUID ...

every ssd runs 220mB/s Read 100mB/s write. benchtest with AJA

Now I build a softwareraid with the two ssds but now the speed is 80 read 60 write !!!!

for two day ist works verry well ( 350 read 200 write ) but now the speed is to slow

now my question :

1) What can be the source of the problem ?

2) need i any Raid Card ?? and if you say yes i need one what kind of card i can use it - the original from apple or any other labels ???

Best regard from the cold Germany !

smarty-s

1. Do you have other drives attached to the SATA ports on the board?
2. Do those drives run simultaneously (same time)?

The above answers could have bearing, but it very well could be a result of the stripe size. What is the stripe size you've set?

You can play around with it (set and test). I'd think you'd want to run it at 128k though (take a close look at the drive specs, and go from there, including reviews, as not all SSD controllers are set the same - it's to do with 512k = n pages * page size. Assuming the page size = 4k, then n = 128k and is what you want to use for the stripe size.

 

[smarty-s]

1. Do you have other drives attached to the SATA ports on the board?
2. Do those drives run simultaneously (same time)?

The above answers could have bearing, but it very well could be a result of the stripe size. What is the stripe size you've set?

You can play around with it (set and test). I'd think you'd want to run it at 128k though (take a close look at the drive specs, and go from there, including reviews, as not all SSD controllers are set the same - it's to do with 512k = n pages * page size. Assuming the page size = 4k, then n = 128k and is what you want to use for the stripe size.

to 1)
yes ! in bay one is the old seagate 1tb Macintosh HDD ( i used it only as a super duper clone for the ssd macsystem ); bay two a old 320GB HDD for data i not used every day and in bay 3+4 are the two crucials

to 2) hmmm ! all volumes are runnig only i made a superduper clone from the raid .

i used the strip size ( Raid Block ) from 32kb

What is my mistake ???

The old HDDs mixed with the ssd by using the same sata controller in the bay ?? or the small Raid Block ?

 

[nanofrog]

to 1)
yes ! in bay one is the old seagate 1tb Macintosh HDD ( i used it only as a super duper clone for the ssd macsystem ); bay two a old 320GB HDD for data i not used every day and in bay 3+4 are the two crucials

to 2) hmmm ! all volumes are runnig only i made a superduper clone from the raid .

i used the strip size ( Raid Block ) from 32kb

What is my mistake ???

The old HDDs mixed with the ssd by using the same sata controller in the bay ?? or the small Raid Block ?

Block size.

You'll need to research the drive, and see what the best setting is. But 32k is going to be too small I think. 64k is the most common (usually the default = balance of performance/capacity for mechanical).

For example, if it were an Intel X25, the best stripe size would be 128k. There's articles out there BTW (Tom's Hardware IIRC).

 

[chmilar]

I have some RAID SSD questions for Nanofrog:

I am anticipating getting a '10 MacPro, when they eventually show up in the Apple Store. I do a lot of work on large images in Photoshop (16000x12000 pixels), so I want some fast storage for Photoshop's scratch space. It also looks like using SSD for boot and applications improves speed.

Since there is no seek time for SSD's, does it make sense to use one Volume for everything? For example:

With an Areca 1212 card and 4 SSD's (Intel Extreme, OWC, or OCZ) striped, used as one Volume for boot, apps, and Photoshop scratch.

Is there any advantage to partitioning the RAID into a scratch volume, and boot/apps volume?

Or should the Photoshop scratch and boot/apps go onto completely separate drives? Historically, this is recommended, but it seems that this advice may no longer be valid for SSD drives.

(I will also have some old-fashioned drives connected to the standard SATA controller for additional storage, and to back up the SSD RAID.)

 

[nanofrog]

I am anticipating getting a '10 MacPro, when they eventually show up in the Apple Store. I do a lot of work on large images in Photoshop (16000x12000 pixels), so I want some fast storage for Photoshop's scratch space. It also looks like using SSD for boot and applications improves speed.

Since there is no seek time for SSD's, does it make sense to use one Volume for everything? For example:

With an Areca 1212 card and 4 SSD's (Intel Extreme, OWC, or OCZ) striped, used as one Volume for boot, apps, and Photoshop scratch.

Is there any advantage to partitioning the RAID into a scratch volume, and boot/apps volume?

Or should the Photoshop scratch and boot/apps go onto completely separate drives? Historically, this is recommended, but it seems that this advice may no longer be valid for SSD drives.

(I will also have some old-fashioned drives connected to the standard SATA controller for additional storage, and to back up the SSD RAID.)

SSD is the fastest storage medium for random access there is. So it's great for OS/applications.

But given the nature of Flash, it's not the advisable way to go for high writes (which scratch would be). Then there's the cost/GB to consider.

So it's best to place the scratch and data on mechanical drives. They're more stable in high write conditions and the cost/GB is quite low.

As per attaching 4x SSD's on an ARC-1212, it's possible (processor should be fast enough @ 800MHz for a stripe set). But leave it in a single logical drive (no partitions). Partitions can make sense with mechanical, but even then, only under certain conditions. I'd set scratch and data to the same set.

But where you get into "old school" with Adobe is actually the need for scratch space. Adequate RAM will significantly reduce the need, as it was a stop-gap performance technique developed when memory was really expensive (not financially feasible). RAM's come way down, and it's not needed like it was anymore.

Hope this helps.

 

[chmilar]

Thanks Nano!

I mentioned using SSD for Photoshop scratch because of this article:

http://www.josephholmes.com/news-fastphotoshop.html

Of course, when CS5 comes out then OS X users will finally have a 64-bit Photoshop, which should obviate the need for scratch, if the computer is packed with RAM. With the 32-bit address limitation of CS4, Photoshop only gives a working space of about 3.2GB. My photos start out at 1.6GB, so with some layers, I am quickly into using scratch space.

 

[nanofrog]

Thanks Nano!

I mentioned using SSD for Photoshop scratch because of this article:

http://www.josephholmes.com/news-fastphotoshop.html

Of course, when CS5 comes out then OS X users will finally have a 64-bit Photoshop, which should obviate the need for scratch, if the computer is packed with RAM. With the 32-bit address limitation of CS4, Photoshop only gives a working space of about 3.2GB. My photos start out at 1.6GB, so with some layers, I am quickly into using scratch space.

Search the forum about creating RAM disks on your system. It helps with 32bit CS4 from what's been posted (there's a how-to in MR somewhere). It's a way to get more of your RAM recognized (and used) by 32bit Adobe applications.

You can use SSD if you wish, but it could be running at the worst performance settings of the drives (depends on file size), and I don't envy the wear to the drives due to the write cycles. SSD's are still immature technology, and doesn't yet have full support cross platform (any OS; Windows for example supports SSD's now, but as I understand it, OS X does NOT).

64bit of course will solve this (memory capacity limit), and there's a few others that have indicated they're waiting for it to release as well.

Good luck.

 

[chmilar]

Thanks again!

It sounds like using SSD for scratch space is not worthwhile. However, I will still look at using them for the boot/apps volume.

I hadn't thought about using a ramdisk to get extra performance until CS5 arrives, but that sounds like a better temporary solution. My current workstation is a G5 with 6.5 GB of RAM, so a ramdisk is not a solution there, but when I get a '10 MacPro I will put at least 12 GB in it.

 

[nanofrog]

Thanks again!

It sounds like using SSD for scratch space is not worthwhile. However, I will still look at using them for the boot/apps volume.

I hadn't thought about using a ramdisk to get extra performance until CS5 arrives, but that sounds like a better temporary solution. My current workstation is a G5 with 6.5 GB of RAM, so a ramdisk is not a solution there, but when I get a '10 MacPro I will put at least 12 GB in it.

Good luck with it, and hopefully, CS5 will debut shortly.

 

[VirtualRain]

Search the forum about creating RAM disks on your system. It helps with 32bit CS4 from what's been posted (there's a how-to in MR somewhere). It's a way to get more of your RAM recognized (and used) by 32bit Adobe applications.

I came across this info on RAM Disks some time ago which may be relevant... while a RAM Disk may benchmark fast, it's not all it's cracked up to be with OSX doing effective RAM caching of disk storage anyway...

From a former Apple employee...

That thing is snake oil, as are the vast majority of ramdisk products on OS X. Designing a ramdisk that works well on OS X is remarkably difficult because backing a block device into wired memory causes the contents to be double buffered above it in the Unified Buffer Cache.

For transient data on systems with no VM pressure, what will happen is the file is created, the object backing it sits in the UBC, it might get synched to disk, but unless you are running low on ram it stays in ram as well. That is why you see no speed increases, all you are doing is eliminating the background asynch writeout, and you are wasting a lot of ram to do it. More importantly, if you are actually creating a wired ram disk you are eating a ton of kernel address space which can be an issue if you have a lot of memory (large page tables) or several video cards.

Source... http://www.ocztechnologyforum.com/fo...ad.php?t=52845

 

[nanofrog]

I came across this info on RAM Disks some time ago which may be relevant... while a RAM Disk may benchmark fast, it's not all it's cracked up to be with OSX doing effective RAM caching of disk storage anyway...

I was going on a post made some time back, where the poster indicated it actually did improve matters.

Beyond that, I've never tried to look into OS X's underpinnings for this type of usage (I've no personal need to do so, as the software I need that really should be 64 bit, already is).

 

[VirtualRain]

I was going on a post made some time back, where the poster indicated it actually did improve matters.

Beyond that, I've never tried to look into OS X's underpinnings for this type of usage (I've no personal need to do so, as the software I need that really should be 64 bit, already is).

Yes... 64-bit FTW! Perhaps a 64-bit version of FCP and/or CS5 will come in time for NAB in less than a month.

 

[nanofrog]

Yes... 64-bit FTW! Perhaps a 64-bit version of FCP and/or CS5 will come in time for NAB in less than a month.

I've no idea when it would release (I don't follow it since I don't use it). I'd look at it and ... How to make it work?

But hopefully it will show up soon, as there seems to be a fair few members here that would love to have it (useful to them, not just want it).

 

[toddbe]

SSD and other drives

The Apple Store genius guy told me you CANNOT have a SSD with other hard drives in a Mac Pro. Is that true?

 

[nanofrog]

The Apple Store genius guy told me you CANNOT have a SSD with other hard drives in a Mac Pro. Is that true?

That's not true at all.