SSDs and RAID 0 - advice on HDDs please

[Brammers]

Hi all,

I'd like to pick your brains regarding HDs if you may.  

Currently I use a very old drive for boot, OS and scratch and its performance isn't great.  I have my docs, images and settings on a separate drive which is mirrored to form a mechanical backup and I use online storage for a proper backup, so I'm happy here.  I'd like to reorganise my 'working' space - the area where I'll place import files to and work on them.

I was thinking of the following setup:

2x 500GP Spinpoint F3s in RAID 0 for OS + Apps  = £72
1x 32GB Corsair Extreme X32 for scratch (220 Read 135 write)  = £100

I've already maxed out my mobo's RAM, and I regularly work on very large pano files.  £200 is my max budget.

How does the above solution look and would you reccomend anything different?  Is 32gb large enough for a scratch drive for Windows and PS?  

Cheers!

[ErikKaffehr]

Hi,

I'd suggest that the SDD may really help. Putting scratch disk on a separate disk is probably a good idea. RAID 0 makes your system faster but increases probability of loosing data by a factor of two.

I would measure disk transfer time. Lets say that you have 30 MB/s which may be like an old 2.5" disk. So it will read a 30 MByte RAW image in a second. If you raid it and reach 60MB/s you can read the same file in 0.5 second. Does it take 10 seconds? If so increasing disk speed would not help.

Putting paging and scratch on different disk would reduce need for head movement which is very slow. SDDs don't need to reposition head so they would be to great advantage, is my guess. Regarding Panos I'd suggest that you download and try Autopano Pro or PtGui. Using a real panorama optimized application really makes a difference.

That said, I used to use AutoPano Pro for large panoramas, like two dozen 24 MP images stitched together. On my old iMac with 3 GByte RAM it could take like 4-5 hours on my new MacPro with Xeon Quad and 16 GByte of memory the same work takes perhaps twenty minutes

Best regards
Erik

Hi all,

I'd like to pick your brains regarding HDs if you may.  

Currently I use a very old drive for boot, OS and scratch and its performance isn't great.  I have my docs, images and settings on a separate drive which is mirrored to form a mechanical backup and I use online storage for a proper backup, so I'm happy here.  I'd like to reorganise my 'working' space - the area where I'll place import files to and work on them.

I was thinking of the following setup:

2x 500GP Spinpoint F3s in RAID 0 for OS + Apps  = £72
1x 32GB Corsair Extreme X32 for scratch (220 Read 135 write)  = £100

I've already maxed out my mobo's RAM, and I regularly work on very large pano files.  £200 is my max budget.

How does the above solution look and would you reccomend anything different?  Is 32gb large enough for a scratch drive for Windows and PS?  

Cheers!

[nemophoto]

I've used a RAID 0 and have an SSD drive for scratch disk. These are my thoughts: I haven't noticed a huge improvement using an SSD for a scratch disk over a conventional drive. Logic says I should, but I find the bottleneck is actually the spped of the processor, the bandwidth of memory and how quickly it can utilize the scratch disk. That said, I wouldn't discourage you from an SSD. 32GB might be a little small, depending upon what you do, (mine is 128GB), but should work. If you do massive images, stitched together and a zillion layers, 32GB is too small. Adobe says you need up to 5-times an image size for scratch -- i.e. a 1GB image uses 5GB.

Regarding the RAID, my personal experience was not great, and I actually had better speed results with a fast single hard drive. (The overhead of swapping reads and writes back and forth between drives seemed like to defeated the supposed advantage of two drives.) Additionally, there was something funky with the RAID (hardware, software??) and I could never fully complete a system backup, or run a full virus scan (no I didn't have a virus). I couldn't even fully clone the drive onto a single drive to replace the RAID (at least under Windows). I actually had to find a disk cloning program that operated under DOS to get rid of my RAID. For that reason, I've never really recommended RAIDs to people.

[Brammers]

Thanks for those replies.

To give a few more details as to my spec, I already use PTGUI Pro and I'm not particularly fussed about the time that it takes ot create the panos - I can leave the machine on and go and do something else.

What I am concerned about is manipulating the image in PS4 and LR after the large file has been created.  At the moment this could go a lot faster.  

My machine is reasonable - 3ghz quad-core with 8GB RAM.  I'm not sure I've ever stitched 2 dozen 24mp files together before, but I've certainly done 1 dozen, and the resulting files are tricky to handle.

nemo - I've done a fair bit of reading on RAID 0 and people seem pretty much split down the middle - those who think it works well and those who don't.  Maybe I'll save that one for later.  I intended to use this drive also for the files that I'm currently working on, moving them onto the slower, large single drive when they were finished.  It would be nice if I could get some extra speed here.  If I don't get along with it, I can always sell one of the drives.

I'm a little concerned about 32gb not being enough...  If scratch files are 5x the size of the real thing that means I can create 6gig panos - I 'think' that should be ok...  This 64gb Samsung claims 220read and 120 write - would that be a better bet?

[bradleygibson]

Hmm...

My suggestion would be to up your RAM on a 64-bit version of Windows.  Photoshop CS4 will install as 64-bit on 64-bit Windows and will bypass the 2/3GB barrier.  This way you'll reduce the need to swap to disk (SSD or otherwise) in the first place.

Note that SSD performance degrades signficantly over time unless 1) your OS knows how to tell the SSD driver to erase unneeded cells 2) the driver receives and understands that specific command (the command is Trim) and 3) The SSD drive also needs to know how to use this command.  AFAIK, only Windows 7 and limited drivers and disks support this, and none support it in any RAID configuration.

Third, as long as you're doing hardware RAID 0, it's hard to see how your I/O wouldn't be faster than without it.  Note that you're halving the reliability of the system, though, because if either disk fails, the volume becomes inaccessbile.

Not trying to dissuade you; just letting you know that (unfortunately) some of what you want to do is still bleeding edge.  You might find a 24GB+ RAM 64-bit system also does the trick for you.

-Brad

[Christopher]

SSDs are great, the cheaper solution for speed is RAID 0. If it's only speed than nothing beats a larger SSD Raid 0 platform.

If some really feel that their single disk is faster, than something is wrong. Perhaps some mistakes or error when setting up the settings.

When it comes to the limiting factor of current systems it is nearly ALWAYS the Hardisk. Nothing else.

[Brammers]

Thanks again for the replies.

More RAM would be an expensive proposition at this time - I've maxed my current mid-range board out at 8gb and I'd need a new mobo to add more.  If I did that I'd probably want to go to DDR3 to make the upgrade worthwhile...  That can come later if I still need speed and if I earn some money off some of these prints

I'm getting roughly a 50/50 split on RAID 0 being worthwhile or not - a lot of people seem to think it's a lot of hassle.  I've ordered the 2 F3s and I'll see how it goes.

I've not ordered an SSD for the moment, mostly because the ones I was looking at aren't in stock.  Assuming I have the funds for a 64gb SSD and a 500GB Raid 0 setup, how would you allocate OS, Apps and Scratch across that?  I'm currently thinking OS + Apps on the RAID and scratch on the SSD, but OS on the SSD and Apps + Scratch on the RAID is also an option.

Cheers all!

[Christopher]

Thanks again for the replies.

More RAM would be an expensive proposition at this time - I've maxed my current mid-range board out at 8gb and I'd need a new mobo to add more.  If I did that I'd probably want to go to DDR3 to make the upgrade worthwhile...  That can come later if I still need speed and if I earn some money off some of these prints

I'm getting roughly a 50/50 split on RAID 0 being worthwhile or not - a lot of people seem to think it's a lot of hassle.  I've ordered the 2 F3s and I'll see how it goes.

I've not ordered an SSD for the moment, mostly because the ones I was looking at aren't in stock.  Assuming I have the funds for a 64gb SSD and a 500GB Raid 0 setup, how would you allocate OS, Apps and Scratch across that?  I'm currently thinking OS + Apps on the RAID and scratch on the SSD, but OS on the SSD and Apps + Scratch on the RAID is also an option.

Cheers all!

Well I could certainly be wrong, because I have no idea which board you have, but shouldn't you be able to use 12 or 16Gb ram ?

[Brammers]

Well I could certainly be wrong, because I have no idea which board you have, but shouldn't you be able to use 12 or 16Gb ram ?

You're right, my board supports 16gb, but it only has 4 slots.  4x2Gb was reasonably cheap, but 4x4gb is crazy expensive.  It would be cheaper to swap out the motherboard and this isn't something I want to do at the moment.

I've read elsewhere the RAID isn't great for a scratch disk because a scratch disk isn't about I/O throughput, but instead needs good random access times.  If this is the case then I'd be best loading my apps and OS from the RAID array and adding a scratch disk in the future - does this go with what you've heard?

[fike]

I have had very good luck with my small 30GB SSD as a PS scratch disk and for PTGui processing.  I use it for both source files and temp files with PTGui.  My speeds are dramatically faster because I was severely IO bound with traditional hard drives.  I also have 8GB of RAM on a 64 bit Vista machine.  A stitch that once took 10 minutes, takes fewer than 2 minutes by using the OCZ Vertex 30GB drive.

Quality and speed on SSDs is highly variable and the Trim issues affect some brands more than others.  The simple story is to buy an Intel X25 or an OCZ drive.  Other brands are frequently poor. For a long and detailed discussion of the issues, see here http://anandtech.com/storage/showdoc.aspx?i=3631 .  The short version is that the chipsets on Intel X25 and OCZ Vertex drives are very good and minimize the Trim issue.  Others degrade substantially over time.

My vote is for the SSD.  I always like to go for the simplest solution available, particularly if it is a home-built solution.

[Brammers]

I have had very good luck with my small 30GB SSD as a PS scratch disk and for PTGui processing.  I use it for both source files and temp files with PTGui.  My speeds are dramatically faster because I was severely IO bound with traditional hard drives.  I also have 8GB of RAM on a 64 bit Vista machine.  A stitch that once took 10 minutes, takes fewer than 2 minutes by using the OCZ Vertex 30GB drive.

Quality and speed on SSDs is highly variable and the Trim issues affect some brands more than others.  The simple story is to buy an Intel X25 or an OCZ drive.  Other brands are frequently poor. For a long and detailed discussion of the issues, see here http://anandtech.com/storage/showdoc.aspx?i=3631 .  The short version is that the chipsets on Intel X25 and OCZ Vertex drives are very good and minimize the Trim issue.  Others degrade substantially over time.

My vote is for the SSD.  I always like to go for the simplest solution available, particularly if it is a home-built solution.

Hi fike,

Good to hear your SSD is working well for you.  I presume you process your panos, probably in something like PS4, after you've stitched them.  Could you elaborate as to how the performance changed there with the SSD scratch disk?

I've had a good read of that Anandtech article, but even though it came out in August I get the feeling things have already moved on - 2 of the most talked about drives aren't in there!  Anyway, I'm going to work with the RAID for the while, which was also needed, and have another look at SSDs in the new year - most of the reasonably priced ones are out of stock at the moment.

[ErikKaffehr]

Hi,

RAID 0 is fast on continuous file transfers but slow seek times. SSDs are fast on data transfer and have zero seek time.

http://macperformanceguide.com/index.html has a lot of good ideas about performance, even if it's Mac oriented physics are the same for the Mac and Windows. On Mac Photoshop is still 32-bit while the CS4 on Windows is 64-bits so it will use memory much more efficiently on 64-bit Windows.

It should be possible to get a decent motherboard for around 150 box and a decent CPU for another 100-200. I bought 16 GByte of memory for around 600 USD while I was in the US. May be worth considering an upgrade.

Best regards
Erik

SSDs are great, the cheaper solution for speed is RAID 0. If it's only speed than nothing beats a larger SSD Raid 0 platform.

If some really feel that their single disk is faster, than something is wrong. Perhaps some mistakes or error when setting up the settings.

When it comes to the limiting factor of current systems it is nearly ALWAYS the Hardisk. Nothing else.

[titan]

I've read elsewhere the RAID isn't great for a scratch disk because a scratch disk isn't about I/O throughput, but instead needs good random access times.  If this is the case then I'd be best loading my apps and OS from the RAID array and adding a scratch disk in the future - does this go with what you've heard?

No hard drive, or arrangement of hard drives, is really great as a scratch disk.

SSD would be great as a scratch disk. Seek times are generally in the tenth of a millisecond.

A RAID can be made of HDDs or SSDs. So, it really isn't RAID itself that isn't great as a scratch space, but the hardware of which the RAID consists.

One change I'd make to your arrangement: OS, applications and scratch/page file on the SSD. Everything else would be stored on the HDD.

[bradleygibson]

RAID 0 is fast on continuous file transfers but slow seek times. SSDs are fast on data transfer and have zero seek time.

Neither of these statements is quite true--RAID0 is not the cause of slow seek times--seek times are limited by the drives themselves.  Mechanical (spinning HDDs) are relatively slow.  RAID 0 with SSD's is quite a different matter.

Access times (historically seek time + latency) for SSDs is typically on the order of ~100x lower than consumer mechanical HDDs at around 0.1ms.

[fike]

I really think that the SSDs are a good idea.  This page made me buy the OCZ Vertex drive as my scratch disk:

http://anandtech.com/storage/showdoc.aspx?i=3631&p=9

The real world PCMark HDD test suite shows really minimal loss in performance of an old drive, and this is WITHOUT TRIM.

[Christopher]

I really think that the SSDs are a good idea.  This page made me buy the OCZ Vertex drive as my scratch disk:

http://anandtech.com/storage/showdoc.aspx?i=3631&p=9

The real world PCMark HDD test suite shows really minimal loss in performance of an old drive, and this is WITHOUT TRIM.

Ok before arguing in any direction just have a look at the following tests: http://macperformanceguide.com/Reviews-SSD....html#Photoshop

It shows pretty clearly that RAID is vital for a Scratch disk, it also shows that normal HDDs in RAID 0 beat 3 SSDs in RAID 0. I don't even start to compare the prize difference. Than another point which is left out is that, SSDs without TRIM as Scratch would soon be a disaster. Just think about it. SSDs without TRIM loose performance once they are filled up and partly reused. A scratch disk would do nothing else than the worst cas for SSD, just being rewritten over and over again without being ever Cleared because of the missing TRIM command.


Once we would be able use TRIM in a RAID array, all things change quite a bit. However there is no promise from ANY company that this will ever happen. So I personally would not go out spend 1000K on a SSD System RAID or Scratch RAID, which will lose performance over time more and more, mostly we don't even have a clue how much can be lost in a 6 months real world test using SSDs under Workstation conditions. (Main reason I'm trying to figure out different ways in the other thread)

[Jack Flesher]

Lloyd did a lot of testing on this and we spent a lot of time discussing it.  Bottom line conclusion for me was that the performance gain of a 2x32G SSD scratch over my existing 4x32G of the fastest outer rim on a set of spinners was probably not worth the cost of the SSD's when I took into account the actual amount of time my machine was having to tag the scratch partition.  IOW, if you tag it continuously, then perhaps the 2xSSD is a good solution.  If you're more like me and use CS say 25% of the time you're on your machine, and tag scratch say 30% of the time you use CS, then it's probably not worth the expense.  Of course this assumes you have a 4-drive stripe in place to begin with or are willing to implement one -- but even 4x2TB Hitachi drives right now are cheaper than 2x128 SSD's...  Starting fresh, with smaller SSD's now getting cheaper, it may make sense for some.  OTOH, with CS5 due out soon, one would hope they've fixed it to better utilize onboard RAM in Mac's -- if so, a dedicated scratch partition may become a very low percentage need...

[Plekto]

You want raid 1 for your boot drive if for no other reason than it's a total PITA to restore and rebuild a drive/OS.

1 - each drive needs to be on its own channel.  Built-in RAID on most motherboards fights with itself for I/O otherwise.  That's simple enough, though, as most boards have two connectors for just that.  3 or more really requires its own controller card, which is a whole other issue.  But we're not talking about that now, so it's simple.  2 drives and 2 channels.  This gives you good fast access - same write as your normal drive but 2x the speed or better for reading.(latency goes down to raid 0 levels for reading but not writing)

2 - You need a swap drive.  This can be a physical ram disk of 2-8GB or a SSD.  Toss your swap file and your temp directories on it.  This also needs to be on a completely different controller from the RAID array so that they don't fight each other.  Most motherboards, though, have major issues with raid and non-raid at the same time, so you need to do a little research here.  Since this isn't a boot drive, you can also get by with an ATA interface or a cheap controller card.   Once you have it sorted out, just having the swap file and virtual memory/temp spaces/etc all NOT clogging up your boot drive is a good 2-3X speed increase.

Even doing this with an old crappy hard drive is a noticeable improvement.  Or just setting aside 1GB memory as a soft ramdisk(as opposed to a hard one like a ram-drive) can be enough.  Windows 7 makes this easy as well, so a 3/1 GIG setup is not a huge headache to accomplish. (since the maximum for a 32 bit process is 2GB normally, it's a good way to speed up things for often no more than the cost of the ramdisk software.

Again, this may mean 4 drives - 2 OS(array), a swap, and a large storage drive.  Some motherboards are not truly capable of handling four different drives at once.  Mine, for instance, won't, which is why my large storage drive is external. (though it does handle the main raid 1 and the swap fine, more gives it a headache)

3 - The RAID need to be RAID-compatible drives.  WD for instance, makes drives that are made to work better with cheap on-board RAID controllers.  They drop out of the array less often as a result.  You can of course run these just fine as single drives.  And any dedicated RAID card will also work fine with normal or RAID type drives, but those that are bootable and reliable can run a couple of hundred dollars.  Now, they are worth every penny, but most people can't afford them for home use.

[Jack Flesher]

You want raid 1 for your boot drive if for no other reason than it's a total PITA to restore and rebuild a drive/OS.

All you need to do with Mac is copy the drive to another partition and it will boot.  Carbon Copy CLoner or Super Duper do this easily and you can schedule it, no need for an actual RAID 1 set-up.  Obviously Windows is more complicated.  

2 - You need a swap drive.  This can be a physical ram disk of 2-8GB or a SSD.  Toss your swap file and your temp directories on it.  This also needs to be on a completely different controller from the RAID array so that they don't fight each other.  Most motherboards, though, have major issues with raid and non-raid at the same time, so you need to do a little research here.  Since this isn't a boot drive, you can also get by with an ATA interface or a cheap controller card.   Once you have it sorted out, just having the swap file and virtual memory/temp spaces/etc all NOT clogging up your boot drive is a good 2-3X speed increase.

Again, not with Macs --- you can use the OS software to raid partitions.  Lloyd and I tested RAM disks and they fell WAY short in the performance compared to even a simple 2-drive stripe (RAID-0) on a pair of off-the-shelf SATA 2 spinners, at least on Mac.

3 - The RAID need to be RAID-compatible drives.  WD for instance, makes drives that are made to work better with cheap on-board RAID controllers.  They drop out of the array less often as a result.  You can of course run these just fine as single drives.  And any dedicated RAID card will also work fine with normal or RAID type drives, but those that are bootable and reliable can run a couple of hundred dollars.  Now, they are worth every penny, but most people can't afford them for home use.

Not necessarily. I am running my OS on a pair of WD 640 Caviar Black drives in RAID-0, not the RE versions -- again using the OS RAID capability, no controller card and I get very fast boot, I/O and a huge, fast desktop for dropping stuff on.  My image storage array is on a 4-drive RAID-0 of WD Caviar Blue drives -- two partitions with the fastest outer partition of each drive in it's own dedicated 4-drive R-0 array for scratch, the larger inner portions in a separate R-0 for large, fast image storage and access, again OS RAID, not RE drives, basic off the shelf drives and with 4 of them, very fast.  Of course since that's working images in R-0 which is NOT redundant, it is backed up locally.

[Christopher]

All you need to do with Mac is copy the drive to another partition and it will boot.  Carbon Copy CLoner or Super Duper do this easily and you can schedule it, no need for an actual RAID 1 set-up.  Obviously Windows is more complicated.  


Again, not with Macs --- you can use the OS software to raid partitions.  Lloyd and I tested RAM disks and they fell WAY short in the performance compared to even a simple 2-drive stripe (RAID-0) on a pair of off-the-shelf SATA 2 spinners, at least on Mac.


Not necessarily. I am running my OS on a pair of WD 640 Caviar Black drives in RAID-0, not the RE versions -- again using the OS RAID capability, no controller card and I get very fast boot, I/O and a huge, fast desktop for dropping stuff on.  My image storage array is on a 4-drive RAID-0 of WD Caviar Blue drives -- two partitions with the fastest outer partition of each drive in it's own dedicated 4-drive R-0 array for scratch, the larger inner portions in a separate R-0 for large, fast image storage and access, again OS RAID, not RE drives, basic off the shelf drives and with 4 of them, very fast.  Of course since that's working images in R-0 which is NOT redundant, it is backed up locally.

Well I don't see any need for RAID 1 in any application. Rebuilding a OS with windows 7 takes me around 1 hour. I think restoring a mac backup should be even quicker. So I really think RAID 1 for a OS just just a waste of a drive.

I also would add, that the normal RAID controller on a main board does a very good job with RAID 0. I would not buy a external raid card for that purpose. However the second we enter something like RAID 5 a additional RAID card is a very good choice.