Superfast Scratch Drive? Or separate cache and media drives?

Hey guys,

I’m in the final stages of getting my new Mac Pro 5,1 system set up, and I’m wanting to optimise my drive layout for the smoothest possible performance when working in Davinci Resolve.

My system's drives are as follows:

- 240GB SSD Boot Drive
- 18TB RAID (around 400MB/sec read, 370MB/sec write)
- 2x 1.92TB PM863 SSDs on a Sonnet Tempo Pro PCIe Card (around 500MB/sec individually or 1000MB/sec in RAID 0)

What I’m trying to figure out, is the best way to arrange my cache, media and project files for the smoothest performance possible.

The way I see it, there are three basic setups I could use:

1)
- 240GB SSD Boot Drive = Just OS and Applications
- 18TB RAID: Near storage, holding backup of media and project files, and exports
- 4TB SSD RAID: Superfast RAID storing all media, project and cache files

2)
- 240GB SSD Boot Drive = Just OS and Applications
- 18TB RAID: Near storage, holding backup of media and project files, and exports
- 1x 1.92TB SSD: Storing all media and project files
- 1x 1.92TB SSD: Storing all cache files

3)
- 240GB SSD Boot Drive = Just OS and Applications
- 18TB RAID: Near storage, holding media files, project files, and exports
- 4TB SSD RAID: Superfast RAID just for cache files

Which setup would you recommend? Are the bottlenecks of having media files and cache files on the same drive better overcome by having them all on a single superfast SSD RAID? By splitting them over two separate (but slower) SSDs volumes on the same PCIe card? Or by having the media on the slower HDD RAID, and leaving the superfast SSD RAID just for caching duties?

I’d appreciate any advice (as my brain’s already turned to mush from my current research on the topic).

Cheers,

Mark

Hi.

It depends on the media.
Are you gonna work with 4k EXR or RED Weapon 8K files a lot, or do you have standard HD resolution only.

I have media drives with 250MB/s for all my HD stuff and some 4k.
For real 4k, which will be ProRes or DNxHR in my case, I have a 400-500MB/s RAID.

My cache drive is a single 2GB SSD with 430MB/s which I'd like to be faster really. I also use this as a temporal final render target drive.

On my computer GPU and CPU is the bottleneck but will be exchanged ASAP.
I'll then add a faster cache drive, too.


Hope this helps

The media will be a bit of a mix, everything from 1080p/2k ProRes4444, to 4k XAVC, to uncompressed 2.8k Arriraw, with the occasional bit of 5-6k Redcode, and 4k SonyRaw. I'm not doing anything with EXR, or in P3 colourspace yet. Predominantly though, it'll be 2k ProRes4444 and 2.8k Arriraw (because I own an Alexa Studio).

I'm a cinematographer by trade, so apart from the odd unsolicited post-job, I'm primarily just grading the projects I shoot - which means that I'm rarely dealing with more than one or two projects simultaneously, and my data/project-management requirements are rather less intense than a full-time colourist's (apart from when I have 1.5-2.5 hour narrative film timelines to deal with).

I've pretty well maxed-out the rest of the machine:

- Titan X 12GB
- 12-core 3.46Ghz
- 64GB RAM
- Decklink 4k
- 4-lane USB3 Card
- 32" Asus PA329Q

So the drive layout (for caching/media/project files) is basically the last bottleneck to minimise (as best I can).

If you're not doing feature length 1TB cache will be sufficient.

I'd use a fast cache with 1-2 TB and a 200-300MB/s media drive.

Just in case I'm happy to have 400 MB/s media drives. It's a 4 HDD external RAID.

Which format are you caching to?

Even if it's not Uncompressed, but you grade for HDR, the minimum is Prores or DNxHR 444 HDR (DNxHR HQX is not enough!!!). I'm on Windows, so caching to DNxHR 444 HDR I need a solid 400 MBps sustained read speed from the cache drive in order to get the full 50 fps. A HDD RAID 0 - even if capable of up to 700 NBps like mine - will not keep up with 400 MBps without the read speed fluctuations, affecting the playback fps...

Piotr

I'm generally caching to ProResHQ.

So you think that having the Media Files on the 400MB/s HDD RAID and the cache on the 1000MB/s SSD RAID would be sufficient then?

Would separating them out like that offer any performance advantages over having everything (media files and cache) on the 1000MB/s RAID?

I'm also curious as to whether not RAIDing the SSDs, and keeping one for caching and the other for media files might work (that would put both on 500MB/s solid state drives) would the slower, but separated SSDs offer any performance advantages over having a faster RAIDed cache drive and a slower HDD RAID for media?

So you think that having the Media Files on the 400MB/s HDD RAID and the cache on the 1000MB/s SSD RAID would be sufficient then?

Would separating them out like that offer any performance advantages over having everything (media files and cache) on the 1000MB/s RAID?

Yes - that's what I do, and all is fine; the HDD RAID is fast enough for playing back media that do not need caching in the first place, while a 1000 MBps cache drive will will play back cached media w/o any problems. Keeping media separate from cache can be beneficial, too - the system never reads and writes to the same physical volume simultaneously, and housekeeping is easier.

Piotr

UHD ProRes 444 60fps is about 400MB/sec.
If ProRes444 and 60fps is max what you will do then this is some reference level for your cache speed requirements.
Good SSD will do, or 3x HDDs in RAID0 (2 maybe bit on the edge).

Good SSD will do, or 3x HDDs in RAID0 (2 maybe bit on the edge).

My requirements with DNxHR 444 are roughly the same (some 360 MBps), but even with my 4x WD Black RAID 0 sustained playback with this throughput is difficult - and it deteriorates with time (heads reading the inner tracks, files becoming fragmented, etc.). Even though when new and almost empty, the same RAID 0 reported up to 700 MBps reads...

Piotr

So is 500MB/s likely to be fast enough to support the cache rendering in real time? If so, would it make more sense to keep the media files on one 1.92TB SSD and the cache files on the other?

That way they wouldn't be reading and writing to the same drive, but would still have enough speed for realtime playback - have I got that right?

Mark, there is no such thing like "cache rendering in real time" - if this would be possible, playback of the graded/edited project with full speed (i.e. in real time) would be possible as well, so why cache at all?

When we talk 400 MBps read speed, we mean real time playback from cache drive with full fps (that's what cache is for). So basically, Resolve reads your media with filters and effects added in grading process, and renders it to the cache drive - it does it with roughly the same speed as when you export to a format comparable with what you've chosen for caching; depending on the original media codec and resolution, the grading applied (e.g. Noise Reduction will slow it down considerably), and you computer power (CPU mainly for decoding, GPU mainly for encoding). Only then can Resolve play back you project in real time - but it does so from the cache drive...

I hope it helps

Piotr

Of course, that makes total sense. Thanks for clarifying Piotr.

The reference to "scratch" or cache drives suggests a Premiere Pro user(?) Note that Resolve operates differently; it doesn't have the same automatic dependence on scratch drives for playback as Premiere and other systems. All playback is from the media drives, unless otherwise instructed.

So unless you're optimizing media or routinely caching nodes and timelines, there may be nothing in your cache folder but audio wave forms. Note also that, at least on Windows, caching is not proving reliable, for some users -- links to the files are lost, from one boot to another. A "superfast scratch drive" would not currently be useful in that case.

Thanks John, great to know. I'm currently editing a couple of projects in Premiere (which I'm still very new to and getting my head around, as I'm primarily a FCPX guy for editing).

This new rig is primarily for Resolve (which is where I spend the overwhelming majority of my post-production time). So do you think going the single superfast SSD RAID for media and caching would be the best way to go Resolve-wise?

So do you think going the single superfast SSD RAID for media and caching would be the best way to go Resolve-wise?

However you set it up, I don't see a compelling reason to distinguish between media and "scratch" drives in Resolve, if your main concern is playback. Having separate physical drives for exports, etc., would be another issue.

I'd assign the cache folders to one or more of the media drives, or the the superfast RAID if that's the only media drive, and see how it goes.

Personally I always separated the media from the caches and I could separate the render "user" from the "smarts". The same goes for the gallery.

Personally I always separated the media from the caches and I could separate the render "user" from the "smarts". The same goes for the gallery.

What is your thought process behind separating the media from the caches Jean?

I simply try to parallelize the best access to disks and to linearize the reads / writes on disks.

X HDDs for media: 10TB internal + 6TB external
2 X SSDs raid0 for render Media composer but also suport for medias that require heavy readings (multicam)
1 X M.2 NVMe cache drive for Davinci Resolve. If we could separate the User cache from Smart, I'll have another Raid0.

All HDDs are in 7200 RPM / cache 64 Mo.

But most importantly: Project setting => general option => cache frame in optimized media: dnXHR 444-HDR. For my workflow : is OK.

Hi,

modern Motherboards have plenty of SATA-Connections.

Why not using 4 x 960 GByte SSD RAID0 instead of 2 x 1.92 TBytes?

Okay it's a bit more expensive, but (theoretical) 2000+ MBytes/second r/w speed could be very interesting for resolve (and maybe for pagefile.sys in case of less memory)

Doesn't it?

Thanks
Peter

Takes more space, produces more heat...
Still, as valid choice as 2x 1.92TB.

4 x SSD RAID0: For the next Christmas. Yet as it must be nice ...

I'm configuring a new machine right now.

I'll have:

- 1 SSD for OS and progs (256 or 512GB with 4-500MB/s)
- 4x WD RED 6TB HDDs in RAID0 for 24TB of media storage up to 600MB/s
- 1x Samsung SM961 M2 1TB as a hi-speed cache-disk with up to 1800MB/s write speed

I'll add another 2 TB SSD as a render out disk soon.
This way I won't need external storage even for bigger projects.

4 x SSD RAID0: For the next Christmas. Yet as it must be nice ...

2 x 1,92 TB = 2 x 520,- € = 1040,- €

4 x 960 GB = 4 x 270,- € = 1080,- €

Double Speed for 40,- € ...


I don't think, the money is a big fact in the decision of those two possibilities.

Thanks
Peter

- 4x WD RED 6TB HDDs in RAID0 for 24TB of media storage up to 600MB/s

I assume you still at this point have some other media copy as these 4 drives in RAID 0 are risky business.

There are new interesting drives from Toshiba:

http://www.notebookcheck.net/Toshiba-un ... 258.0.html

I'm new to Resolve and BM workflows... having issues getting real time playback in Resolve 14 using a 1TB SSD (Sandisk Ultra II ~ 500mbs) for media (HD 3:1 RAW @ 24-60fps) over USB-3. BM Disk Speed Test shows roughly 40mbs... really bad. How do I dedicate the internal SSD for cache in Resolve? Will that take care of it, or is my computer the problem? Anything else I should be aware of?

Computer specs below
---
Mid 2014 MBP, 2.8 Intel i7
16GB DDR3, NVIDIA GeForce GT 750M
1TB internal SSD

Thanks!


EDIT: With only the SSD plugged into my computer, my speeds were around 325 write / 425 read respectively. I didn't realize how much that affected performance. Also, changing my GPU Processing Mode from 'Auto' to 'Metal' made a noticeable improvement. Still can't seem to get 60fps to playback without chop. Decreasing resolution doesn't seem to help all that much either. Any other thoughts?

Bringing this thread back to life . . . after reading this, I still had questions but since I already had them going here . . . viewtopic.php?f=18&t=124099&p=687923#p687923
. . . would you kindly review and advise, please? I am building a Resolve machine and have questions in regard to system, cache, and media drives.