Archive for the ‘NAS’ Category

Storage Volume Read/Write Speeds for Video Editing

Friday, October 18th, 2013


  • I expect my new Crucial M500 SSD will satisfy my multicamera HD video editing requirements far more than my old 7-disk RAID.
    • In neither case should their bandwidths be the bottleneck for say one live (raw HD-SDI) HD channel or say 10 simultaneous ProRes files.
    • In addition, the SSD should avoid the Disk-RAID’s  issues over seek-time (latency). framentation, moving parts, noise, heating (unwelcome in summer) and power supply requirements.
  • That’s the theory …it waits to be tested …when I get a time-break to backup everything then install and test it.


Some video bandwidth requirements:

  • Raw HD-SDI of 720p 25 frames/sec or 1080i 50 fields/sec: 188 MB/s == 1.5Gbps
  • ProRes: approx 15 MB/s == 120 Mbps
  • XDCAM-EX: VBR, around 4.4 MB/s == 35 Mbps

Sustained sequential (as video ought mostly to be) data read/write speed estimates:

  • RAID of 7200 rpm disks:
    • 7 x raid5 plus 1 hot-spare: around 600 MB/s == 4.8Gbps
    • In my case, I get 400 MB/s == 3.2Gbps.
      • That’s around two live HD channels or 25 ProRes HD files, though in practice one would expect the need for headroom-margin, hence say one live HD channel or 10 Prores files?  Not bad.}
  • SSD:
    • For my Crucial M500 960GB Laptop-internal SSD:
      • SeqRead: Over 375MB/s == 3Gbps
      • SeqWrite: Over 500 MB/s == 4Gbps
    • And no issues over seek-time (latency) or framentation or moving parts or noise or power supply.
  • USB3
    • 625 MB/s == 5Gbps
    • 7200rpm disk > USB3: 110MB/s == 880 Mbps
  • Local 7200 rpm drive:
    • 40-100 MB/s == 320–800 Mbps, for most modern drive types.
  • NAS: 100MB/s == 800 Mbps advertised, under 50 MB/s == 400 Mbps  in practice.
    • But there can also be latency issues.
  • USB2:
    • 60 MB/s ==”480 Mbps” in theory…
    • …but in practice, as seen by user, is more like 38 MB/s == 300 Mbps.


Shared Storage Options for Windows & Mac Video Editing Collaboration

Friday, October 18th, 2013

In summary:

There’s no magic option, each workstation needs a local storage volume with block-level data access (as opposed to simply file-level access) and formatted to a file system that is native (doesn’t require translation) to that workstation’s operating system.  Migration and collaboration imply file copying/synchronization, which implies read-access to the “foreign” file-system.  Mac OS can read NTFS, Winows can only read HFS+ via third-party add-on utilities.  Furthermore, for speed and responsiveness appropriate to video editing, the local storage should ideally be RAID or SSD.  In either case, it is possible to split the local storage (e.g. via partitioning) into more than one file-system.  At least, that worked on the mutiple occasions I have taken that approach, and have not been aware of any issues.

In greater detail:

Consider the challenge of setting up a shared data storage volume (e.g. RAID array or SSD) for video editing, such that either Windows or Mac computers can connect to it, and a video project started on (and saved to) on one of those operating systems (OS) can be continued on the other (and vice versa).

My current solution is to split the drive into separate volumes, one for each OS.  For example I have done this on RAIDs of various kinds and on an internal drive for Mac systems bootable to either Mac OS or (via Boot Camp) to Windows.  In the case of RAIDs I was advised against this by my system supplier, but got the impression they were just being defensive, not knowing of any definite issues, and to my knowledge I did not experience any issues.

It is is not practical to have just one volume (necessarily in that case, one file-system format), because:

  • Mac OS on its own is able to read NTFS but cannot write to it.
    • This is a show-stopper.  Some of the major video editing applications (e.g. NLEs), slightly disturbingly, may use (or for some functionality, even depend on) read/write access to source-files and the folders containing them.
      • I initially, naively, imagined that video editing systems etc. would only ever read source media files, not write to them, or to the folders containing them.  However that proved very naive indeed…
        • In Apple/Mac’s (erstwhile) Final Cut Pro 7 I regularly used their (moving) image stabilization effect, SmoothCam.  Its analysis phased was typically slow and heavy – not something one would wish to repeat.  The result was a “sidecar” file of similar forename to the analyzed source file, but a different extension, placed in the same folder as the source file.
        • I’m not certain, but got the feeling that maybe the source file (or folder) meta data, such as permissions or somekind of interpretation-change to media files in the quicktime ([.mov] mmedia format.
      • Certainly, Adobe (on Windows and Mac) could adulterate both files (by appending XMP data – being an Adobe media metadata dialect in XML) and the folders they occurred in (depending on uder-configuration) in terms of sidecar-files.
      • Sony Vegas also generates sidecar-files, e.g. for audio peaks.
  • File system translation add-ons can add Windows read/write access to HFS+ (ordinarily it could not even read it) and add Mac OS write access to NTFS (ordinarily it could only read it), but not sufficiently transparent/seamless for big real-time data access as required for demanding video editing endeavours.
    • File system translation add-ons (to operating systems) exist, such as MacDrive, to allow Windows to read/write Mac OS, or Tuxera NTFS, Paragon NTFS or Parallels for Mac to enable it to read/write NTFS, but these (reportedly, and in part of my experience) only really work well for standard “Office” type applications, not so well for heavy (big andd real-time) data applications such as video editing, where they can impede the data throughput.  Doh!
    • Some people have experienced obscure issues of application functionality, beyond data-movement speed issues.
    • {Also, I am concerned over the (unknown/imagined/potential) risk that the “alien” operating system and/or its translation utility might alter the file system in some way that upsets its appearance to the “home” operating system.}
  • FAT is universal but is a riskier option:
    • FAT is un-journaled, hence risks loss not only of individual files but of whole volume (integrity).
      • In video editing, corruption could be disastrous to a project, not only in terms of possible data-loss or time wasting and project delays on data recovery, but also in terms of “weird” effects during editing, such as poor responsiveness to commands, whose cause the user may not appreciate. or even an increased risk of unacceptable flaws in the final product.
    • FAT32 is essentially obsolete, because its maximum file size is (1 bit under) 4GB.
    • exFAT, a kind of “FAT64” is practical, and indeed a big successful corporate Mac-based production company once supplied me with many GB of footage on an exFAT-formatted external disk.
      • The largest file I have so far stored there is 40GB.  No problems.
  • NAS (Network-Attached Storage) sounds at first an easy option, but in my experience they impede big real-time data throughput (as stated earlier for “file system tyranslation” add-ons). Double-Doh!
    • Such devices only permit file-level access.  Consequently, the client systems can e.g. create or retrieve folders and files, but cannot e.g. format the device or address it in terms of lower-level data structures.
    • A likely explanation for the “impedement” of a NAS (to data responsiveness and throughput) is that such devices store in a local format (typically they run linux) that is invisible to the client, then translate to an appropriate protocol for each operating system accessing it.  They normally incorporate a bunch of such protocols.  As always, translation => overhead.
    • Other options, such as SAN and iSCSI, instead of providing file-level access to the client systems, instead offer the lower level of data block access.  Thus they appear to the client system as would any local storage device, and can be formatted as appropriate to the client system.
  • One suggestion I saw was to use a Seagate GoFlex drive, which can be used (read/write) with both Mac and Windows.  But the supplier’s FAQ (about that drive) indicates that it depends upon a translator utility for the Mac:
    •  If you would like to be able to “shuttle” data back and forth between a Mac and a PC, a special driver needs to be installed onto the Mac that allows it to access a Windows-formatted drive (i.e. NTFS). Time Machine will not work in this case, nor will Memeo Premium software for Mac. However, if you want your GoFlex solution to also work with TimeMachine, the drive will need to be reformatted to HFS+ journaled.

So I guess there is no “magic storage” option, my main work setup will have to remain based on separate volumes for each OS.

When transferring an editing project from one OS to another, the following actions will be necessary:

  • Copy any absent or updated files across.
    • e.g. via a file-synch utility such as Syncovery.
  • Allow time etc. for possible file re-linking, re-indexing, re-preview generation, re-“SmoothCam” (or equivalent).
    • This aspect is down to the editing application etc., as opposed to the operating or file systems themselves.
  • Ensure any effects used in the edit are present on both systems.
    • If so then these should presumably still work…


WD Link: Successor to WD Discovery

Monday, February 4th, 2013

WD Link Setup is the successor to WD Discovery, for detecting WD NAS drives and mapping them to drive-letters.

RAID / NAS etc Ideas

Saturday, July 7th, 2012

Some RAID ideas: