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  1. #1
    Mac hard drive test utilities and CoreStorage

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    Mac hard drive test utilities and CoreStorage
    I saw the following note a few days ago:

    Maconlysource Blog Archive SCSC Releases a Major Update of Scannerz for Mac OS X

    Is Scannerz the only drive testing program on the market offering full support for CoreStorage right now? I looked at the TechTool Pro site and it said fully encrypted volumes needed to be tested on an eDrive, like they're foreign (meaning strange) drives, and some of their comments about Fusion and other Core Storage technologies seemed somewhat sketchy. The same appears true for Drive Genius.

    I got a copy of the demo version of Scannerz from MacUpdate, and they take CoreStorage components and separate them out to be tested individually, along with a single entry for the entire thing. If you have a Fusion Drive, that means you'll get an entry for the SSD, an entry for the HD, and an entry for the whole thing. It sounds kind of squirrelly but when I thought about it, it seemed to make sense. The SSD isn't likely to fail (or is it??? ) but the HD might. This way you can scan the HD as a standalone component.


    Out of curiosity, any idea why it's taking the "big boys" so long to get around to addressing this completely?

  2. #2
    Mac hard drive test utilities and CoreStorage

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    Probably several reasons:

    1. Small companies like SCSC (makers of Scannerz) likely need to be out in front of the other guys just to make themselves stand out, plus the business for them is likely something they need where the "big boys" as you call them can afford to lose a percentage of customers.

    2. Although CoreStorage is a "hot topic" and "leading edge technology," the reality is few will ever use it or care about it. If you use full volume encryption you will need it. If you're creating your own Fusion Drive clone, you will need it. If you're creating a big virtual drive out of several smaller drives, you will need it. The reality, however, is that most speed freaks will opt for a pure SSD, not an SSD that has an albatross around its neck called a hard drive (think Fusion drive). Users that need space can likely get all they want by simply buying a big hard drive - they're cheap now and easier to maintain than a string of drives together. Last but not least, how many people encrypt their drives? I would bet that the number of people using CoreStorage is less than 5%.

    I've been a fan of Scannerz for about 2 years now. The others will likely get around to supporting it in their own time, but for now they can likely afford to lose a tiny percentage of customers.

  3. #3
    Mac hard drive test utilities and CoreStorage

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    I saw this post today and started thinking about it. It's good that these guys have a product that can test a fusion drive on a component by component basis, but I think file recovery of any kind has the potential to be a nightmare that a lot of advocates of the Fusion drive are overlooking. This of course doesn't have anything to do with the Scannerz app.

    The Fusion drive works by disk management that's transferring data from the "real" hard drive to the SSD when active, and then apparently back again when more inactive. Let's just say for the sake of argument that one component, either the SSD or the actual hard drive fails. What are you left with?

    Todays applications use shared libraries that are loaded on demand. If an application that's frequently loaded it but doesn't use all of its libraries until needed, then those libraries would likely remain on the HD. If the SSD in the Fusion fails, then the main part of your app is gone with a lot of little libraries hanging around on the HD. If the HD fails, then you're stuck with an app that will eventually want to reload those now gone libraries. Some applications also rely on other applications, and the same problem still exists.

    It's certainly good that you can use this tool to find the bad part of a Fusion drive, but users need to be aware of the fact that if one of the components fails, it seems to me you're totally hosed. I had a hard drive develop bad sectors and when I attempted to recover data, I could get most of it. I could tell what couldn't be recovered because when a copy from the bad drive to another drive would hit a bad region, the OS would issue and input/output error saying it couldn't read the bad drive. I could tell what was bad and what needed to be replaced or renewed. It was a PIA, but it was doable. This is NOT doable with a Fusion drive.

    I don't think the Fusion drive is a good implementation. I would have thought they would have put the core OS and applications on the SSD and then used an HD with a very large cache on it in conjunction with it. In other words, I would have locked items that are mostly read and rarely written to on the SSD and let the HD handle anything with a lot of writes. This would put most user data on the HD. In this manner you could at least figure out what could and couldn't be recovered.

    Moral of the story: If you have a Fusion Drive, keep good backups, and on an HD, too (I still don't trust SSDs yet)

  4. #4
    Mac hard drive test utilities and CoreStorage
    chscag's Avatar
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    Good post. I disagree with one thing though..... SSDs by themselves can be trusted. Their reliability is actually very high - at least for the quality SSDs.

    However, I do agree with you regarding the Fusion drive. Another thing that's overlooked is the nightmare scenario of getting inside an iMac in order to replace a Fusion drive, or for that matter, any hard drive. One almost has to buy Apple Care to protect their investment. We'll get a better feel for the overall reliability of Fusion drives as the newer iMacs that have them begin to settle down and burn in.

  5. #5
    Mac hard drive test utilities and CoreStorage

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    Another problem with Core Storage is what does it do if the drives are all "regular" hard drives. I took two old USB drives I had and combined them into one logical volume. I like the idea, but Apple has implemented a "secret disk management" scheme that may or may not render this type of configuration not only useless but actually much worse than a regular hard drive.

    If you've looked at the Core Storage (CS) docs, one drive is the "primary" and all the others you use are secondaries. You can apparently add more than one HD to an SSD configuration, with the SSD being the "primary." The idea is to transfer frequently accessed files to the SSD, but what if it's not an SSD.

    I hate to tell you this guys, but virtual volumes and drives where multiple drives or partitions are merged into one apparent drive has been around in the Unix world for a very long, long time. The question is, does CS recognize an HD only virtual configuration and knock off it's "magical disk management?" Why is this a big deal? Because if it implements the same type of re-arranging of data onto the "primary" drive in a CS configuration, there's no performance gain, in fact you're just causing the drive to have to move data from one regular HD to another regular HD, which really just amounts to an actual performance loss. In other words, it's stupid.

    And now for my rant:

    GOD, I HATE MOUNTAIN LION!!!!!!!!!!!!

    This is the most bug ridden piece of crap I've seen since Windows '95. If I attach a camera with pictures on it to iPhoto, I get the following:

    1. iPhoto sometimes doesn't acknowledge the camera being present
    2. Sometimes it will see the camera and report there are no photos
    3. Sometimes it will crash
    4. Sometimes it will actually notice there are photos there and actually load them!!!


    I used to be able to create a note in Mail and transfer it to my iPhone. Not any longer. You MUST either setup an imap account or use iCloud. Apparently it never occurred to Apple that some people work in secure environments and doing either of these is not allowed.

    Oh Well, two solutions:
    1. Get rid of the iPhone (there are about 346 at my facility) and replace it with something we can use.
    2. BOW DOWN to the overlords at Apple and simply say to ourselves, "Golly Jeepers, I guess we're not good enough to do this any more...the geniuses at Apple are simply to advanced for our pathetic ways.


    It's a brilliant idea, try to force people onto the iCloud to such an extent that they're likely going to lose customers using iPhones to switch to Androids.

    And how about them thar OS bugs? One day I had Mail, Safari, and TextEdit open, and suddenly the system comes to a complete crawl. I check Activity Monitor and the system has used up all 8GB of RAM and is now swapping. This has happened about 5 times.

    And then there are the visual improvements Lion and Mountain Lion have to offer, namely gray instead of color. Gray scroll bars, gray icons, is color confusing?

    ...oh well, I guess I've gotten off topic.

  6. #6
    Mac hard drive test utilities and CoreStorage
    Dysfunction's Avatar
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    CS is effectively (from what I can briefly ascertain) tiered storage. This isn't exactly a new concept. Rotating hot extents to higher cost, faster storage, and cold extents to cheaper mass storage.. Is well.. An enterprise storage type operation these days (probably lower end than enterprise actually). Personally, although my portable is ssd, I think this is a pretty cool idea. More so in larger desktops or Mac Pros than notebooks and I'm glad to see this hit the consumer level.

    That said, I obviously haven't played with the CS implementation of this type of data management, and have plenty of complaints about mountain lion too... So I have no idea it there is the full implementation of tiered storage (which is to what you're referring to I believe), there certainly is on the fusion drive, but not sure how that's accomplished at this point.

    On and my iPad, yea it's autocorrect sucks for many words. On and I can't wait until consumer drives are FDE at the device level, rather than the OS.
    mike
    This machine kills fascists
    Got # ? phear the command line!

  7. #7
    Mac hard drive test utilities and CoreStorage

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    Too many to list. Typically use an Intel iMac for most of my stuff and a Mini for web video.
    I've been using OS X since 2002 and tonight, for the first time ever, under Mountain Lion of course, TextEdit crashed for no apparent reason. In all this time, I have never had TextEdit, which has got to be the simplest of apps available crash. I know there's some stunt you can pull with any Apple app that will cause an application to crash if you enter "File:" followed by 3 '/' characters, but I didn't do that.

    I've really been waiting for Apple to release another version which would hopefully fix a lot of these problems, but I'm tired of waiting, and if their work continues their trend toward sloppiness, there's little reason for me to think it will be any better.

    Right now my main system has ML and SL on the main drive. Tomorrow night at this time, ML will be cloned to a FireWire drive and the volume now holding ML will be Lion. I know some people have had trouble with Lion, but I haven't. If Apple ever gets around to fixing ML properly, then maybe I'll consider swapping back. IMHO it simply can't be trusted.

    ...a TextEdit crash???? Seriously???? This is ridiculous!

  8. #8
    Mac hard drive test utilities and CoreStorage
    chscag's Avatar
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    If Apple ever gets around to fixing ML properly, then maybe I'll consider swapping back. IMHO it simply can't be trusted.
    They're not likely to fix it in the way you want. Instead, we'll probably see the next iteration of a "Big Cat" version of OS X late this year. (10.9.X) And, that may introduce other problems.

  9. #9
    Mac hard drive test utilities and CoreStorage
    Dysfunction's Avatar
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    Quote Originally Posted by chscag View Post
    They're not likely to fix it in the way you want. Instead, we'll probably see the next iteration of a "Big Cat" version of OS X late this year. (10.9.X) And, that may introduce other problems.
    We'll see, with ML they went from big cat to lessor cat. Maybe the next iteration will be "tabby"
    mike
    This machine kills fascists
    Got # ? phear the command line!

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