Macrium's view on the recent SMR disk controversy

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    Macrium's  view on the recent SMR disk controversy

    Macrium's view on the recent SMR disk controversy


    Posted: 30 Apr 2020
    In recent weeks there has been significant controversy caused by reports that a number of big hardware vendors are quietly shipping SMR disks in their NAS (Network Attached Storage) products.

    The reasons for this are not particularly surprising. By using SMR, vendors can, as this Ars Technica article does a good job of explaining, “eke out higher storage densities, netting more TB capacity on the same number of platters — or fewer platters, for the same amount of TB.” This is at the cost of performance, as well as a number of other compatibility issues.

    While the companies involved have responded to criticisms from both users and sections of the tech press, we thought the controversy would be a good opportunity to take a closer look at current trends and issues across the spinning disk market, including SMR, TRIM, and RAID.

    There’s undoubtedly a lot of technical complexity at play here. This makes it particularly hard to determine the extent to which the companies alleged to have been using SMR were acting with malicious intent or merely failed to properly anticipate product issues for users. However, because such hardware can have a significant impact on performance and system resilience, understanding the differences between them is absolutely essential. For this reason, we believe manufacturers should have been clear from the start which devices utilised SMR.

    What is SMR (Shingled Magnetic Recording)?

    Innovation in magnetic disk technology is always moving towards higher data density and lower cost per GB. SMR continues this trend. However, unlike other recent incremental improvements, it has a significant impact on device performance.

    A traditional disk with standard, non-overlapping tracks is typically called a CMR (or sometimes PMR) disk. Each CMR track (and a sector within a track) can be written without overwriting neighbouring tracks; the ‘cost’ of an update is only the time to slew the disk head and the sector to rotate under the head.

    SMR uses the property that a narrower track can be read than the minimum written width. By writing overlapped tracks, the achievable data density can be significantly increased. This increase in density should in principle reduce the cost per GB and a small power reduction per GB where the number of platters can be reduced.

    There is a cost, however; to write an update, all the tracks have to be re-written. The primary mitigation is to divide the shingled areas into zones. This limits the re-write to the extent of the zone, instead of the entire disk surface.

    To update a byte on the disk, the entire zone must be read, updated in memory, and then written back out to disk. This is known as write amplification. Flash media is similarly impacted, although to a lesser extent. Due to its structure, erasure must be applied to a whole page of memory.
    Read more. Source: Macrium’s view on the recent SMR disk controversy
    sygnus21's Avatar Posted By: sygnus21
    30 Apr 2020

  1. Compumind's Avatar
    Posts : 2,717
    Windows 10 Pro x64, Various Linux Builds, Networking, Storage, Cybersecurity Specialty.
       #1

    I have a couple of 4 TB WD drives that use SMR and they work well.

      My Computer

  2. jh30uk's Avatar
    Posts : 263
    Windows 10
       #2

    The fact is they are slower and did not disclose they had used these in some lines of their HDD's.

    I personally would not buy any SMR drives, I would rather have a smaller CMR drive or pay more for a CMR larger drive.
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  3. sygnus21's Avatar
    Posts : 5,407
    Win 10 Pro (x64) 20H2 (19042.928)
    Thread Starter
       #3

    jh30uk said:
    The fact is they are slower and did not disclose they had used these in some lines of their HDD's.

    I personally would not buy any SMR drives, I would rather have a smaller CMR drive or pay more for a CMR larger drive.
    Same here; I'd rather have CMR drives.

    Anyway early 2019 (Feb) I bought a WD 4 Bay NAS and 4 WD Red Pro 6TB drives. I need to check if those are SMR drives. Everybody is talking about the Red drives, but no mention of the Red Pro's so...

    Been meaning to look them up, but frankly the NAS has been running 24/7 in Raid 10 without issue so it's not been a huge worry. That said, I am curious so I guess I'll look into them after this post.

    Edit: Found it. The 6TB Red Pro's are CMR

    On WD Red NAS Drives - Western Digital Corporate Blog
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  4. eLPuSHeR's Avatar
    Posts : 2,450
    Windows 10 Home x64
       #4

    How do you know if a drive is SMR or CMR?
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  5. jimbo45's Avatar
    Posts : 10,491
    Windows / Linux : Arch Linux
       #5

    Hi there
    I think some old English Bard once said around 16th cent "A little learning is a dangerous thing" -- Still true today.

    The basic scence might be OK but it's how you apply it.

    Presumably if you install an adequate cache size in the HDD then you can effectively negate any impact on performance -- Most sensible OS's these days use some sophisticated A.I (Artificial Intelligence) algorithms to in "plain English" - get a feel of what the computer user is doing and is therefore able to predict reasonably well what data the user will want to access next.

    So the OS "Prefetches" this data into the disk cache so it's there quickly available when required -- and during idle cpu cycles the next bit of data will be read from HDD into the cache. All modern OS's these days overlap I/O processing with CPU bound processes. The cache is usually very fast memory - far faster than the actual HDD access.

    So when buying HDD's these days -- as well as the RPM rate ( a faster spinner will reach the relevant track/sector quicker) it's important to go for HDD's with the largest cache size possible.

    If the cache size is anything like reasonable -- 128 MB is usually enough on consumer grade HDD's -- anything smaller -- don't bother -- then the whole issue of SMR is irrelevant.

    Cheers
    jimbo
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  6. Trust_No1's Avatar
    Posts : 630
       #6

    I have an SUV drive manufactured by Ford, plenty fast and lots of storage.

    I find it hard to keep tires on the WD, Seagate and Toshiba drives , so I'm good.
      My Computer

  7. Compumind's Avatar
    Posts : 2,717
    Windows 10 Pro x64, Various Linux Builds, Networking, Storage, Cybersecurity Specialty.
       #7

    jh30uk said:
    The fact is they are slower and did not disclose they had used these in some lines of their HDD's.
    I personally would not buy any SMR drives, I would rather have a smaller CMR drive or pay more for a CMR larger drive.
    How much slower are the SMR internal drives versus the CMR?

    The two I have are external USB 3.0 SMR HDD's. The rest are external SSD's.

    Just curious.

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  8. sygnus21's Avatar
    Posts : 5,407
    Win 10 Pro (x64) 20H2 (19042.928)
    Thread Starter
       #8

    eLPuSHeR said:
    How do you know if a drive is SMR or CMR?
    WD has a page telling you what drives are what as linked above your reply

    As for other drive manufacturers I'm sure they have something as well.
      My Computers

  9. mta3006's Avatar
    Posts : 956
    W10 Pro v1903
       #9

    Trust_No1 said:
    I have an SUV drive manufactured by Ford, plenty fast and lots of storage.
      My Computers


 
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