Re: Portable version degrading
Hi,
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Defragmentation won't extend drive life. Instead, it makes it a bit faster for drives to return data you need. For hard drives, once the required region gets the attention of a read/write head, the head will read continuously unless told to stop. Ideally, the head can (and should) do this in one sitting, but sometimes it'll go "mad" if trying to locate fragmented information all over the drive, particularly if you've edited files and the drive decided to store the new bits somewhere else. As for automatic defragmentation, it is controlled by a setting in Optimize Drives. As for accessing related data: depends. If the data you need (or a group of them) is located next to each other, then yes, otherwise the drive will be searched to locate fragments. As for calling me a "professor": I don't deserve this title (I don't have a doctorate in NVDA, let alone computer science or communication studies). Nor it isn't the first time someone gave me this nickname: many years ago, I was called "professor" as I seem to know everything about HumanWare BrailleNote, with some BrailleNote users commenting that I am a Humanware staff when I was just a high school senior. In terms of NVDA, let's just say that this is just a small talk from a certified NVDA Expert; perhaps I should record a tutorial set devoted to NVDA internals. Cheers, Joseph
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From: nvda@nvda.groups.io [mailto:nvda@nvda.groups.io] On Behalf Of ely.r@comcast.net Sent: Friday, January 19, 2018 12:34 PM To: nvda@nvda.groups.io Subject: Re: [nvda] Portable version degrading Professor Joseph, So, first, I will be reading this lecture several time going forward. However, you do a wonderful job of making geeky things reasonably comprehensible. I think in part for me is your slight leaning towards anthropomorphizing file systems, drives and even those little electrons. One question has to do with defragmenting. Does the process help to increase the accessing of related pieces of data? Second, does the process extend drive life to any extent? Last, I promise, I thought I read at some point that systems had made user invoked defragmentation unnecessary. Be that true? Rick the old English teacher who loves Inanimate objects that come to life Dr. Rick Ely TVI, Vision Consultant 451 Rocky Hill Road Florence, MA 01062 &413() 727-3038 -----Original Message----- From: nvda@nvda.groups.io [mailto:nvda@nvda.groups.io] On Behalf Of Joseph Lee Sent: Friday, January 19, 2018 12:19 PM To: nvda@nvda.groups.io Subject: Re: [nvda] Portable version degrading Hi, It'll depend on what type of drive it is. If it's a traditional hard drive, it'll degrade as data moves around, creating the need for defragmentation. This is especially the case when data is repeatedly written and the file system is asked to find new locations to hold the constantly changing data. In case of solid-state drives, it'll degrade if the same region is written repeatedly, as flash memory has limited endurance when it comes to data reads and writes. In case of Roger's issue: a possible contributing factor is constant add-on updates. He uses an add-on that is updated on a regular basis, putting strain on part of the drive where the add-on bits are stored. Thus, some drive sectors are repeatedly bombarded with new information, and one way operating systems will do in this case is move the new data somewhere else on the drive, potentially fragmenting bits of files (I'll explain in a moment). Thus one solution is to not test all add-on updates, but that's a bit risky as Roger is one of the key testers for this add-on I'm talking about. Regarding fragmentation and what not: the following is a bit geeky but I believe you should know about how some parts of a file system (an in extension, operating systems) works, because I believe it'll help folks better understand what might be going on: Storage devices encountered in the wild are typically organized into many parts, typically into blocks of fixed-length units called "sectors". A sector is smallest unit of information that the storage device can present to the outside world, as in how much data can be held on a storage device. For example, when you store a small document on a hard disk drive (HDD) and when you wish to open it in Notepad, Windows will ask a module that's in charge of organizing and interpreting data on a drive (called a file system) to locate the sector where the document (or magnets or flash cells that constitute the document data) is stored and bring it out to you. To you, all you see is the path to the document, but the file system will ask the drive controller (a small computer inside hard disks and other storage devices) to fetch data in a particular sector or region. Depending on what kind of storage medium you're dealing with, reading from disks may involve waiting for a platter with desired sector to come to the attention of a read/write head (a thin magnetic sensor used to detect or make changes to magnetic fields) or peering inside windows and extracting electrons trapped within. This last sentence is a vivid description of how hard disks and solid-state drives really work behind the scenes, respectively. But storage devices are not just meant for reading things for your enjoyment. Without means of storing new things, it becomes useless. Depending on the medium you've got, when you save something to a storage device, the file system in charge of the device will ask the drive controller to either find a spot on a disk filled with magnets and change some magnets, or apply heat pressure to dislodge all cells on a block, erase the block, add new things, and fill the empty block with modified data (including old bits). You can imagine how tedious this can get, but as far as your work is concerned, it is safe and sound. Now imagine you wish to read and write repeatedly on a storage device. The file system will repeatedly ask the drive hardware to fetch data from specific regions, and will look for new locations to store changes. On a hard drive, because there are limited number of heads and it'll take a while for desired magnetic region to come to attention of one, read speed is slow, hence increased latency (latency refers to how long you have to wait for something to happen). When it comes to saving things to HDD's, all the drive needs to do is tell the read/write head to change some magnets wherever it wishes, hence data overriding is possible and easy. But operating systems (rather, file systems) are smarter than that, as we'll see below. In case of solid-state drives, reading data is simple as looking up the address (or sector) where the electrons comprising the data you want is saved (akin to walking down a street grid), so no need to wait for a sensor to wait for something to happen. This is the reason why solid-state drives appear to respond fast when reading something. On the other hand, writing or injecting electrons is very slow because the drive needs to erase the entire block before writing new data. In other words, just changing a letter in a document and saving it to an SSD involves a lot of work, hence SSD's are slower when it comes to writing new things, but because of the underlying technology in use, it is way faster than hard disks. As hinted above, file systems are smarter than drive controllers to some extent. If data is written to a drive, the drive controller will process whatever it comes along its path. But file systems won't let drive controllers get away with that: file systems such as NTFS (New Technology File System) will schedule data writes so it'll have minimal impact on the lifespan of a storage device. For hard disks, it'll try its best to tell the drive to store file data in consecutive locations in one big batch, but that doesn't always work. For SSD's, the file system will ask the drive to storage new information in different cells so all regions can be used equally (at least for storing new information; this is called ware leveling). One way to speed things up is asking the drive to reorganize data so file fragments can be found in consecutive sectors or trim deleted regions so fresh information can be written to more blocks (for HDD's and SSD's, respectively), and this operation itself is tedious and produce bad results if not done correctly and carefully. I do understand the above explanation is a bit geeky, but I believe you need to know some things about how things work. It is also a personal exercise to refresh my memory on certain computer science topics (I majored in it not long ago, and my interests were mostly hardware and operating systems, hence I was sort of naturally drawn to screen reader internals and how it interacts with system software). Cheers, Joseph -----Original Message----- From: nvda@nvda.groups.io [mailto:nvda@nvda.groups.io] On Behalf Of Roger Stewart Sent: Friday, January 19, 2018 7:58 AM To: nvda@nvda.groups.io Subject: Re: [nvda] Portable version degrading The problem with this discussion is my portable version is on an internal hard drive. So why is this degrading? Nothing else on this drive has any trouble and I've checked, and there's no file system errors nor any fragmenting. Roger On 1/19/2018 8:28 AM, Antony Stone wrote: USB drives do need to be unmounted before removing them, otherwiseis the risk of file system corruption. Precisely the same is true forexternal hard drives, floppy disks, or any other writeable medium you cantemporarily attach to a computer.considerably more robust than floppy disks, which is basically what they replaced.can also drop them on the floor with a good deal more confidence of themworking afterwards than if you drop an external hard disk.have plastic caps to put over the contacts or a slider to retract theinto the body.If they're mistreated they'll give as many problems as any othertheir datafiles on USB thumb drives. These things are horrible in terms of workloss than other portable drives, certainly more vulnerable than most backat all or nvda gets very sluggish in responsiveness and this all gets Ito normal after a complete flush and remake of the portable version. say, this never has happened at all with my installed copy on the
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