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iMacs and Fusion Drives
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[Jeremy Garchow] “Still, complaining about 1GB/sec being a hard limit seems a little far fetched.”
I should add that yes, 1 GB/s is a lot of bandwidth.
Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events -
As mentioned, it depends on the system.
In FCP7, you have a choice of how you want things to playback (Dynamic RT, etc). FCPX has a portion of this.
When you playback 6 angles of multicam, it is not 6 full resolution streams of video. Other NLE’s might work differently.
It’s really easy to watch what is happening in Activity Monitor, but that requires a Mac. 😛
🙂
Jeremy
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One note here is that the i/o meter in the Activity Monitor isn’t entirely accurate. I’ve measured faster than theoretically possible i/o over the network when judging from that app.
But I think if you are right. ProRes is a very scalable / dynamic format that will raster down when needed. In multicam you might only read every 4th pixel or something i.e. lowering the bandwidth a lot.
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“Fusion Drive” is a term like “Bootcamp” that encompases several different things, it’s not a single thing or product. A Fusion Drive is made by leveraging CoreStorage, which is sorta like the logical volume manager (LVM2) in linux. CoreStorage is also used to implement full disk encryption.
Either a whole drive, or partition can be designated as a physical volume (PV), and its “space” added to a logical volume group (LVG) to aggregate storage from multiple PVs. From that LVG pool, one or more logical volumes (LV) can be created. So what Apple is doing at the factory is adding one large partition on each of the included SSD and HDDs, as PVs, into a LVG, and then creating a single LV. The LV is formatted HFSJ, so the file system thus extends across two physical devices. So can you do this yourself with your own SSD and HDD if you don’t buy a “Fusion Drive” from Apple? Yes you can. And it can be done with non-Apple branded SSDs and HDDs. But it’s non-obvious how to do this in Disk Utility, and honestly at this point I’ve found enough bugs in Disk Utility once going “off the rails” (it’ll do simple formatting, partitioning, etc of a single disk, OK). But as soon as you start repartitioning, resizing, doing RAID setups, the utility is one of the worst UIs to ever come out of Apple, in my opinion. So I’ve resorted to using the CLI for this.
Much of this is in the coreStorage section of ‘man diskutil’ in Terminal.
The gotcha, of course, is if either the SSD or HDD dies, you lose the whole file system. In effect it’s like the linear or concatenated RAID type. Don’t count on being able to extract any information from the surviving drive. The other thing is that the migration of data from one PV to another, once it’s successfully migrated, is removed from the other PV. Some may wonder what could happen if there were a kernel panic or power failure were to occur during this migration. Only upon successful copy and commit to the PV, is data then removed (technically deallocated) from the other PV.
Also, I’m pretty sure the migration is at an extent level, not a file level. I haven’t read much about this one way or the other, but coreStorage is ignorant of the file system, it’s simply a layer that maps a logical block device to one or more physical block devices, and at least with linux LVM this is done with extents (which are variable size, but default is a 4MB extent).
So if you wanted to intentionally over provision your SSD for wear leveling reasons, or you want a volume exclusively on the SSD or HDD, and a separate volume that’s “fusion” between both drives, yes you can do that. But thus far I haven’t figured out a way to do in the GUI and for other reasons (Bootcamp experiences) I don’t trust Disk Utility aside from really simple tasks on single disks.
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[Walter Soyka] ” I should add that yes, 1 GB/s is a lot of bandwidth.”
Nobody can say that Thunderbolt is not crazy fast bandwidth, it is. But no one should plain ignore that even faster performance is currently available on 4-5 year-old tech via PCIe. And all that isn’t crazy expensive, elitist or unthinkable for current workflows – and these don’t have to be comprised of 4K either. Yes Thunderbolt is more user friendly, with laptop proxy editing collaboration and all, but there was a compromise that was made for that to happen. Let’s see what they’re really giving us back later on. Stay tuned.
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[Jeremy Garchow] “As mentioned, it depends on the system. In FCP7, you have a choice of how you want things to playback (Dynamic RT, etc). FCPX has a portion of this. When you playback 6 angles of multicam, it is not 6 full resolution streams of video. Other NLE’s might work differently.”
We’re not talking about the same thing.
[Jeremy Garchow] “It’s really easy to watch what is happening in Activity Monitor, but that requires a Mac. :-P”
I’ve got a few lying around here somewhere… 🙂
[Erik Lindahl] “But I think if you are right. ProRes is a very scalable / dynamic format that will raster down when needed. In multicam you might only read every 4th pixel or something i.e. lowering the bandwidth a lot.”
Working with scaled rasters can certainly lower bandwidth to/from the GPU, but resolution-on-decode scalability is generally a feature of wavelet-based compression, not DCT-based compression. I am really struggling to think of a way that this could work, but it’s an interesting proposition.
Aren’t we probably talking about automatically-created proxies?
Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events -
Sorry, Howie, I know this all has nothing to do with any of your questions. Welcome to FCPX or Not: The Debate. If you haven’t seen it yet, the FCPX Techniques forum [link] is a great place to discuss actually using the application!
[Christian Schumacher] “Nobody can say that Thunderbolt is not crazy fast bandwidth, it is. But no one should plain ignore that even faster performance is currently available on 4-5 year-old tech via PCIe. And all that isn’t crazy expensive, elitist or unthinkable for current workflows – and these don’t have to be comprised of 4K either. Yes Thunderbolt is more user friendly, with laptop proxy editing collaboration and all, but there was a compromise that was made for that to happen. Let’s see what they’re really giving us back later on. Stay tuned.”
In other news, the keyboard port (USB) is all grown up, and USB 3.1 will be 10Gbps.
https://www.tomshardware.com/news/SuperSpeed-USB-3.0-Thunderbolt-10Gbps-Promoter-Group,23768.html
A couple good quotes:
“We’re really focusing on USB 3.0 — it’s an excellent alternative to Thunderbolt,” said Acer spokeswoman Ruth Rosene. “It’s less expensive, offers comparable bandwidth, charging for devices such as mobile phones, and has a large installed base of accessories and peripherals.”
Meanwhile, Intel seems to be supporting the new USB 3.1 spec despite its Thunderbolt efforts. “The industry has affirmed the strong demand for higher through-put, for user-connected peripherals and docks, by coming together to produce a quality SuperSpeed USB 10 Gbps specification,” said Alex Peleg, Vice President, Intel Architecture Group. “Intel is fully committed to deliver on this request.”
Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog – What I’m thinking when my workstation’s thinking
Creative Cow Forum Host: Live & Stage Events -
[Christian Schumacher] “But no one should plain ignore that even faster performance is currently available on 4-5 year-old tech via PCIe.”
I’m not ignoring it, I am weighing the pros and cons. Do you, personally, saturate an 8x PCIe bandwidth? Is it even possible?
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[Jeremy Garchow] “Do you, personally, saturate an 8x PCIe bandwidth? Is it even possible?”
Apple seems to think so. TB2 is under way now. And Intel and all have plans to go optic and so on, why is that? Isn’t 1,0GB enough?
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[Christian Schumacher] “Apple seems to think so. TB2 is under way now. And Intel and all have plans to go optic and so on, why is that? Isn’t 1,0GB enough?”
For data and for now, I’m saying it is.
TBolt2 still has the same overall bandwidth as TB1, it is just aggregated differently.
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