Film-Tech Forum ARCHIVE: DCP Hard Drive Readability Issues with Venu

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Posted by Brian Rose (Member # 5919) on 10-29-2019, 12:52 PM:

Hi All!

I'm a filmmaker and I make my own DCPs. I use OpenDCP for the creation, and then I put my files on a Linux EXT2 formatted hard drive. Most of the time this process has worked without fail. But almost inevitably, a few complaints crop up, and they are always: "I can't read your hard drive, can you bring another." This gets frustrating after a while because most of the complainants are venues of, shall we say, less than stellar quality, with operators who have questionable skills. I oblige them and create a new drive and all, but it gets to be tiresome.

I'm now dealing with a venue complaining my drive doesn't show anything on it, so I'm going to make them a new drive. This one previously screened at the Gene Siskel center without issue, so I'm pretty sure it's a problem on their end. But is there anything I could be doing to head off issues like this in the future? Should I try formatting in another version of Linux, or is it a folder/naming convention?

Any advice you all might have would be deeply appreciated!

BR

Posted by Harold Hallikainen (Member # 5405) on 10-29-2019, 02:02 PM:

The ISDCF recommendations for distribution drives are at https://isdcf.com/papers/ISDCF-Doc3-Delivery-Recs.pdf .

Harold

Posted by Scott Norwood (Member # 30) on 10-29-2019, 02:21 PM:

Yes, the recommendations linked to above are good.

Are you sending out "advanced format" disks? You really should be sending out 512-bytes-per-sector disks, since not every server knows how to deal with the newer types.

Another possible failure point could be the inode size. This is important for cinemas that use a Windows-based TMS to read the disks. If the inode size is not 128, whatever software they are using that allows Windows to read the ext filesystem will fail.

If I were regularly sending out DCP copies of my movie to different venues, I would probably re-write the disk each time just to ensure that the disk was still physically good (i.e. that it had not been dropped somewhere along the way) and had a clean copy of the movie with no extraneous material. In theory, the servers should mount the content disks as read-only, but it may have been used in a general-purpose computer at some point where the user was not as careful.

Part of the problem here is that it is possible to make a DCP disk that is formatted so that some, but not all, cinema servers will read and/or play the DCP. That leads to plenty of finger-pointing about "it worked at <some other venue>" with festival staff.

In any case, thanks for trying to make this situation better. Having been on the other end of this, I have seen blank disks, HFS+-formatted disks, disks with filesystems but no partition tables, disks with corrupted partition tables, and all sorts of other odd configurations and problems that simply fail to work with most cinema servers. These can often be worked around, but it is a real pain to deal with dozens of these during a "film" festival, where the most problematic exhibition copies are always the ones that arrive at the last minute.

Posted by Leo Enticknap (Member # 534) on 10-29-2019, 03:08 PM:

One problem not mentioned I have encountered many times when making and distributing DCP drives is that some servers and IMSes do not have enough USB bus power to spin up some USB-powered 2.5" portable hard drives. GDC SX-3000s are especially bad: I would guess that at least half the USB-powered hard drives I've hooked to them have failed to spin up. Occasionally when I make DCPs for others, they want me to put them on a 2.5" USB hard drive that they supply, despite my warning of this issue. When the inevitable "it won't ingest" complaints arrive, my first question is if the venue is trying to ingest it into a GDC IMS. The answer is almost always in the affirmative. If you are an arthouse venue that regularly receives DCPs on 2.5" USB-powered drives and you use a GDC IMS, you need to get yourself an externally powered USB hub. Now. Without one, you're on borrowed time until you connect someone's drive and hear the ominous "Bzzzzzz ... click!" of a drive trying to spin up without enough miliamps.

I would advise anyone making and distributing DCPs on physical media to avoid 2.5", USB bus-powered drives, period. Not only do you have this problem, but as boxes full of glass platters and other moving parts, they are vulnerable to damage in shipping. Reputable brand 256GB USB flash sticks that need a small fraction of the power can now be had for $50 (USB3) or $35 (USB2), and you'll save even more shipping them, compared to a spinning rust drive, so there is now simply no rational reason to continue using hard drives for DCP distribution, that I can think of. About 95% of DCPs will fit on a 128GB stick ($20), and 99.9% on a 256GB one. If you have a four-hour, 4K, 3-D, 120 FPS epic you want to send some place, even 512GB flash sticks aren't stratospherically expensive anymore.

For formatting the drives, I would suggest using a native Linux-based system (e.g. CentOS or Ubuntu), and a utility such as PartEd to re-write the MBR and partition table, then create a single content partition occupying the entire drive, which you then format as ext2 or 3, with an inode size of 128 bytes. I have seen many examples of amateur DCP makers buying a drive from Office Depot and then simply reformatting its existing content partition to ext2 or 3, leaving a GPT partition table and/or an EFI partition in place, either of which will cause many models of DCP server to be unable to see the content partition.

Note that in order to nuke a drive that has an EFI partition on it, you'll need to be using a computer that has not booted its operating system in UEFI mode - has to be legacy. The easiest way to achieve this is to repurpose an old, pre-UEFI desktop or laptop, install a free Linux-based desktop OS on it (again, CentOS and Ubuntu are my favorites), and use it simply for preparing DCP distribution drives, perhaps with a LAN connection to the computer or a NAS box that actually holds the DCP files.

Posted by Marcel Birgelen (Member # 6801) on 10-29-2019, 05:53 PM:

Sorry to chime in second or third, but like Scott and Leo already highlighted. Most common issues with servers out there:

- 512 byte sector disks are still a requirement for some of those older servers out there. So make sure your disks are either old-school 512 byte sector disks or make sure they support it in emulation mode if you can't find any.
- Make sure you put an MBR partition table on it, not a GPT one.

Most of the newer systems will work fine with 4K sectors and even GPT partition tables, but it's the older systems or those running old firmware that will probably not read the disk or be able to mount the partition and therefore will not show anything on the disk.

Posted by Dave Macaulay (Member # 813) on 10-30-2019, 10:11 AM:

I've had issues with creating ext2 drives on systems other than servers, especially add-on filesystems for Windows. The permissions apparently get locked to the formatting system so it won't allow use on a server... and I don't know how to fix that. I just use makefs on a server (one that lets you get a full linux terminal, Dolby "Doremi" do but DSS ones don't) and then mount the formatted disk on my PC to store the completed DCP. This has worked for me so far. May not be your problem but something I ran into.
That seems to create the filesystem with the correct settings and MBR and no restrictive permissions.

Posted by Steve Guttag (Member # 268) on 10-30-2019, 11:02 AM:

If you have a Dolby DSS server, you can format a drive (CRU or even USB) with the DSS software itself using the CLI.

Formatting removable drives (USB or CRU) is done from administrator/scripts.
The command is: ./formatStore.sh localhost [Removable | USB]
It takes about 10 minutes per TB so give it some time.

Posted by Carsten Kurz (Member # 5396) on 10-30-2019, 11:47 PM:

What is your 'native' operating system - windows, or OS X?

If you are not a native Linux user, skip the ISDCF file system recommendation and use NTFS (but adhere to all other ISDCF recommendations). Max 2TB drives, MBR partition table, single primary partition.

The current breed of ext2/3 drivers for Windows or Mac OS X are not stable and cause issues.

You should also transition away from Open DCP. There is no development, and it has lost contact to the SMPTE DCP world. Get a go with DCP-o-matic.

Tuxera has a fast, solid and low costs NTFS driver for OS X with write support.

- Carsten

Posted by Marcel Birgelen (Member # 6801) on 10-31-2019, 06:34 AM:

If you don't have a separate machine, you can always spin up a VM with e.g. Ubuntu loaded into it, using free tools like Virtual Box. Make sure you pass thru your USB port, so you can attach external disks via USB directly into the VM.