External Disk Drives
  • Having fallen victim to the allure of 4M PoE cameras, my disk consumption has gone way up. I am currently dumping to a 3Tb external drive (of which 1Tb holds some old Time Machine files), but I am ready to bump my license from 8 to 16 cameras (on a late 2012 i7 mac mini). Aside from lots of disk, the mini seems quite able to handle the load.

    The Black Friday/Cyber Monday deals have produced one contender - 8Tb for $150 = http://a.co/4oPc3yd

    The featured review of the product states:

    The Backup Plus Hub series appears to consist of SMR (Shingled Magnetic Recording) drives.
    ...
    Disadvantages of SMR

    -- Slower random writes. SMR drives use large write heads relative to the width of the tracks of bits, so writing one track affects the next tracks of bits too. This limits SMR drives to sequential writing, where the next tracks don't matter. To do random writes (such as changes to data on the drive already), data must be arranged sequentially in cache, by the drive in this case, and entire sections of the drive must be rewritten sequentially. Some of this can be hidden by the use of large cache on the drive, believed to be 20 GB or more on Seagate SMR drives. Data can be written quickly to cache and then rewritten more slowly to another part of the drive.
    -- Highly variable sequential write speeds, due to the particular ways the drive manages where to put data.

    Is this going to be a fatal flaw for using this for video files?
  • Yes, fatal flaw. Absolutely don't use an SMR based drive in a live video recording application.

    1. The SMR drive's write speed can unpredictably plummet for any given moment as it internally catches up. SMR drives must erase sectors to write new sectors due to their shingled write architecture. For some applications, those intermittent delays are acceptable, but not for live video.

    2. The SMR drives have proven to be prone to failure in high write intensive usage. Multiple TIVO (DVR's) owners who upgraded their drives to SMR units had their drives physically fail in several months. They simply don't have the write endurance needed for video.

    Personally, I use a two 8 TB western digital reds in an external Akitio Thunder2 Duo Pro. That yields very reliable, fast 16 TB of storage. My WD digital reds easily handle continuous recording from 16 2M and 3M cameras with only a fraction of their write speed capability.

    It's not $150 by a long shot, but it is a reliable storage system that is proven to work 24/7 for years. Even via a USB 3 connection, the external is more than fast enough.
  • Yes I have to agree fully with @guykuo here - nothing more for me to add!

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