❶ 请问硬盘是靠什么东西来储存文件的
分类: 电脑/网络 >> 硬件
解析:
硬盘驱动器
是一种采用磁介质的数据存储设备，数据存储在密封于洁净的硬盘驱动器内腔的若干个磁盘片上。这些盘片一般是在以铝为主要成分的片基表面涂上磁性介质所形成，在磁盘片的每一面上，以转动轴为轴心、以一定的磁密度为间隔的若干个同心圆就被划分成磁道（track），每个磁道又被划分为若干个扇区（sector），数据就按扇区存放在硬盘上。说起来，硬盘的工作原理很简单，硬盘可以读取和写入保存数据，写入数据实际上是通过磁头对硬盘片表面的可磁化单元进行磁化，就象录音机的录音过程；不同的是，录音机是将模拟信号顺序地录制在涂有磁介质的磁带上，而硬盘是将二进制的数字信号以环状同心圆轨迹的形式，一圈一圈地记录在涂有磁介质的高速旋转的盘面上。读取数据时，只需把磁头移动到相应的位置读取此处的磁化编码状态即可。
❷ 文件越来越多，电脑磁盘储存空间不足应该怎么办
伴随系统逐渐运行，许多系统文件、备份文件、缓存文件等。用户通过几种途径清理存储空间，提升存储空间。下面小编介绍一下硬盘存储空间不足的解决办法。
三、程序卸载或转移
有些程序占用存储空间很大，平常用户使用概率低，甚至几乎用不到。用户直接卸载长期用不到的程序，一些使用次数不多程序转移到其他盘上，从而释放出不少空间。彻底卸载电脑程序，用户最好使用第三方软件，将系统配置文件和备份文件一起删除。软件管理独立版、驱动人生软件管家、新毒霸管理软件、网络管理软件等都是不错电脑管理软件。这些软件功能强大，灵活管理安装应用程序，快捷安装和升级、卸载，还推荐软件下载。
❸ 长期存储文件用固态还是机械
长期存储文件用固态硬盘还是机械硬盘，主要取决于你的实际需求。
固态硬盘（SSD）和机械硬盘（HDD）都有各自的优势和缺点，所以在选择硬盘时需要根据自己的实际情况来选择。
固态硬盘具有较高的读取速度，能够更快的打开文件和启动电脑，而机械硬盘的优势在于它的容量大，可以存储更多的文件，弯胡也更便宜。
如果你想存储大量的文件，并且不会经常使用这些文件嫌毕，且不对速度有较高要求，那么机械硬盘更适合你。而如果你想要快速访问文件，那么固态硬盘就更适合你。
固态硬盘和机械硬盘都有各自的优势，如果准确地判断出自己的需求，就可以根据需求作出正确的选芹闹芹择，来满足长期存储文件的需求。
❹ 2020-12-02 硬盘如何存储文件
系统中所有内容是以文件（文件夹是特殊的文件）存在的，而文件分为属性（元信息）和内容两部分，磁盘一部分被操作系统虚拟为块用来存储数据，同时也分出一部分虚拟为Inode用来存储文件属性，这样磁盘就分为块区和inode区。
扇区：磁盘存储数据的最小物理单元，每个扇区很小512字节左右。
读取数据：OS要想读取磁盘数据，首先让磁头径向寻道（最慢），然后旋转磁盘（较快），使磁头到达目标扇区，开始读取数据。
磁盘块：OS日常工作中，一个扇区的512字节数据很小，不足以支撑绝大部分工作场景，所以需要频繁读取单个扇区，而磁盘读取数据速度相对CPU处理太慢了，所以读磁盘时一次就多拿出几个扇区（临近的，无需耗费额外时间）的数据，于是在OS层面逻辑虚拟出磁盘块（簇）的概念，一个磁盘块一般对应8个连续扇区（也可4、16个等，由OS决定），这样OS层面就使用磁盘块作为最小数据存储单元。
这样的好处当然是更高效，缺点则是会？
inode：用于存储文件的元信息（除名称外的所有属性，名称存在文件夹的内容中）
Inode number is also known as index number. An inode is a unique number assigned to files and directories while it is created. The inode number will be unique to entire filesystem.
Disk inodes contain the following information:
Owner identifier
Type of file (regular, directory, character or block device)
Access permissions
Times and dates
· file creation time
· last file access time
· last inode modification time
Number of links to the file
Array of pointers to data blocks on disk
File size (in bytes, sometimes also in blocks)
文件：
上文提及文件属性存在磁盘inode区的inode（每个都有编号）内，而内容存储在块区的块中。
文件夹：
作为特殊文件，其组织文件及目录，属性也是存在inode内，而存储的内容是一个包含多个{ 文件名:对应inode Id} 的列表，内容亦存在块区的块中。
这样在OS中查看一个文件（比如/etc/fstab）的内容，大概是：
首先OS获取到根目录的inodeId >在inode区中读取到其属性（某项是内容所在块）>在块区读取到根目录内容>在内容中找到名为/etc对应发inodeId>/etc在inode区的属性>读取到块中/etc的内容（包含/etc/fstab对应inodeId）>/etc/fstab Inode Id > 在inode区读取到/etc/fstab属性 >/etc/fstab块。
可能有误，望指点。
Within each file system, the mapping from names to blocks is handled through a structure called an i-node. There's a pool of these things near the "bottom" (lowest-numbered blocks) of each file system (the very lowest ones are used for housekeeping and labeling purposes we won't describe here). Each i-node describes one file. File data blocks (including directories) live above the i-nodes (in higher-numbered blocks).
Every i-node contains a list of the disk block numbers in the file it describes. (Actually this is a half-truth, only correct for small files, but the rest of the details aren't important here.) Note that the i-node does not contain the name of the file.
Names of files live in directory structures. A directory structure just maps names to i-node numbers. This is why, in Unix, a file can have multiple true names (or hard links); they're just multiple directory entries that happen to point to the same i-node.
refer: https://unix.stackexchange.com/questions/432655/why-does-using-indirect-pointers-in-inodes-not-incur-the-same-amount-of-space
less:by direct list blocks in node?.
large :by two-level indirect block
larger : multi-level indirect block.
The original hierarchy of the inodes levels works roughly like this:
You can store one or a few block numbers directly in the inode. This means you use a few bytes more for the inode, but for small files, you don't have to allocate a complete block, which is mostly empty.
The next level is one indirection: You allocate a block to store the block pointers. Only the address of this indirect block is stored in the inode. This doesn't use somehow "less space", and most filesystems, even early ones, worked like that (have a pointer near the inode/filename which points to a block, which stores the block numbers of the file).
But what do you do when the space in this block runs out? You have to allocate another block, but where do you store the reference to this block? You could just add those references to the inode, but to store largers files, the inode would get large. And you want small inodes, so as many as possible inodes can fit into a single block (less disk access to read more inodes).
So you use a two-level indirect block: You just add one pointer to the inode, then you have a whole block to store pointers to indirect blocks, and the indirect blocks store the block address of the file itself.
And so on, you can add higher-level indirect blocks, or stop at some stage, until you reach the maximal size of a file possible with the structure you want.
So the point is not "use up less space in total", but "use a scheme that uses blocks efficiently for the expected distribution a files wrt. to size, i.e. many small files, some larger files, and very few huge files".
Page tables on the other hand work very differently.
Edit
To answer the questions in the comment:
Data blocks are of fixed sizes (originally 512 bytes, IIRC), which is a multiple of the block size of the underlying harddisks. So data block size can't "decrease".
As I tried to describe above, the whole point of having the inodes not use up too much space is to make inode access faster (or, alternatively, make caching inodes use up less memory - back then when the unix file system with inodes was invented, computers had a lot less memory than today). It's not about somehow saving space in total. As you say yourself, everything has to be stored somewhere, and if it doesn't use up space at location X, it will use up space at location Y.
Just adding a variable number of block pointers to the inode is not practical, because the inode must take up a fixed amount of space - you want to use the inode number to calculate the block address and the offset inside the block where the inode information is stored. You can't do that if every inode has a different size. So there must be some form of indirection.
Page tables work differently because hardware implements them differently - that's just how it is. The hierarchy has a fixed depth, always the same (though sometimes configurable. And while reading a block from disk is slow, that doesn't matter for page tables. So the design issues are completely different.
http://www.cems.uwe.ac.uk/~irjohnso/coursenotes/lrc/internals/filestore/fs3.htm
Assuming, for the purposes of illustration, that each disk data block is 1024 bytes in size, then these ten data block pointers will allow files to be created that are up to 10 Kb in size. As you can see, for the large majority of files it should be possible to access the data with nothing more than a direct lookup required to find the data block that contains any particular data byte.
With this scheme, once a file has grown to 10 Kb, there are only three block pointers in the inode left to use, whatever the eventual size of the file. Obviously, some new arrangement must be found so that the three remaining block pointers will suffice for any realistic file size, while at the same time not degrading the data access time too much.
This goal is achieved by using the idea of indirect block pointers. Specifically, when an 11th data block needs to be allocated to the file, the 11th inode block pointer is used, but instead of pointing to the block which will contain the data, the 11th pointer is a single indirect pointer which points to a data block filled with a list of direct block pointers. In our example, if we assume that a data block number is a 32-bit value, then a list of 256 of them will fit into the single indirect block. This list will point directly to the data blocks for the next 256 Kb of our file. This means that with 11 block pointers in the inode, files of up to 266 Kb (10 + 256) can be created. True, it takes a little longer to access the data beyond the first 10 Kb in the file, but it takes only one extra disk block read to find the position on the disk of the required data.
For files bigger than 266 Kb the double indirect (12th) inode block pointer is used. This is the same idea as the previous inode pointer except that the double indirect pointer points to a list of pointers in a data block, each of which is itself a single indirect block pointer which points to a list of 256 direct block pointers. This means that the 12th inode block pointer gives access to the next 65536 Kb (256x256) of data in our file.
By now, you should be able to spot the pattern and see that when the file grows bigger than 64 Mb (actually 65802 Kb), the inode's 13th data block pointer will be used, but this time as a triple indirect pointer, which will give access to a staggering 16 Gb (256x256x256 Kb) of extra file space. A single file bigger than 16Gb sounds huge. However, even though the calculation we have just done suggests that this file size is possible with the inode layout as given, in fact there are other factors which limit the maximum size of a file to a smaller value than this. For example, the size of a file, in bytes, is stored separately in its inode in a field of type unsigned long. This is a 32-bit number which limits the size of a file to 4 Gb, so that 13 data block pointers in an inode really are enough.
10.4. How a file gets looked up
Now we can look at the file system from the top down. When you open a file (such as, say, /home/esr/WWW/ldp/fundamentals.xml) here is what happens:
Your kernel starts at the root of your Unix file system (in the root partition). It looks for a directory there called ‘home’. Usually ‘home’ is a mount point to a large user partition elsewhere, so it will go there. In the top-level directory structure of that user partition, it will look for a entry called ‘esr’ and extract an i-node number. It will go to that i-node, notice that its associated file data blocks are a directory structure, and look up ‘WWW’. Extracting that i-node, it will go to the corresponding subdirectory and look up ‘ldp’. That will take it to yet another directory i-node. Opening that one, it will find an i-node number for ‘fundamentals.xml’. That i-node is not a directory, but instead holds the list of disk blocks associated with the file.
The surface area of your disk, where it stores data, is divided up something like a dartboard — into circular tracks which are then pie-sliced into sectors. Because tracks near the outer edge have more area than those close to the spindle at the center of the disk, the outer tracks have more sector slices in them than the inner ones. Each sector (or disk block ) has the same size, which under modern Unixes is generally 1 binary K (1024 8-bit bytes). Each disk block has a unique address or disk block number .
Unix divides the disk into disk partitions . Each partition is a continuous span of blocks that's used separately from any other partition, either as a file system or as swap space. The original reasons for partitions had to do with crash recovery in a world of much slower and more error-prone disks; the boundaries between them rece the fraction of your disk likely to become inaccessible or corrupted by a random bad spot on the disk. Nowadays, it's more important that partitions can be declared read-only (preventing an intruder from modifying critical system files) or shared over a network through various means we won't discuss here. The lowest-numbered partition on a disk is often treated specially, as a boot partition where you can put a kernel to be booted.
Each partition is either swap space (used to implement virtual memory ) or a file system used to hold files. Swap-space partitions are just treated as a linear sequence of blocks. File systems, on the other hand, need a way to map file names to sequences of disk blocks. Because files grow, shrink, and change over time, a file's data blocks will not be a linear sequence but may be scattered all over its partition (from wherever the operating system can find a free block when it needs one). This scattering effect is called fragmentation .
Within each file system, the mapping from names to blocks is handled through a structure called an i-node . There's a pool of these things near the "bottom" (lowest-numbered blocks) of each file system (the very lowest ones are used for housekeeping and labeling purposes we won't describe here). Each i-node describes one file. File data blocks (including directories) live above the i-nodes (in higher-numbered blocks).
Every i-node contains a list of the disk block numbers in the file it describes. (Actually this is a half-truth, only correct for small files, but the rest of the details aren't important here.) Note that the i-node does not contain the name of the file.
Names of files live in directory structures . A directory structure just maps names to i-node numbers. This is why, in Unix, a file can have multiple true names (or hard links ); they're just multiple directory entries that happen to point to the same i-node.
In the simplest case, your entire Unix file system lives in just one disk partition. While you'll see this arrangement on some small personal Unix systems, it's unusual. More typical is for it to be spread across several disk partitions, possibly on different physical disks. So, for example, your system may have one small partition where the kernel lives, a slightly larger one where OS utilities live, and a much bigger one where user home directories live.
The only partition you'll have access to immediately after system boot is your root partition , which is (almost always) the one you booted from. It holds the root directory of the file system, the top node from which everything else hangs.
The other partitions in the system have to be attached to this root in order for your entire, multiple-partition file system to be accessible. About midway through the boot process, your Unix will make these non-root partitions accessible. It will mount each one onto a directory on the root partition.
For example, if you have a Unix directory called <tt class="filename">/usr</tt>, it is probably a mount point to a partition that contains many programs installed with your Unix but not required ring initial boot.
❺ 永久储存资料用什么硬盘好
永久储存资料用机械硬盘好。
机械硬盘其实也是用磁来记录信息，那就决定了机械硬盘的可修复性比较高，还有就是机械硬盘在不通电的情况下也能把数据保存十年以上，这就非常的适合长期保存数据了，而且相对固态硬盘来说便宜很多，买一个现成的移动硬盘即可。
硬盘介绍
电脑硬盘是计算机最主要的存储设备。硬盘（港台称之为硬盘，英文名：Hard Disk Drive， 简称HDD，全名温彻斯特式硬盘）由一个或者多个铝制或者玻璃制的盘片组成。这些盘片外覆盖有铁磁性材料。
绝大多数硬盘都是固定硬盘，被永久性地密封固定在硬盘驱动器中。早期的硬盘存储媒介是可替换的，不过今日典型的硬盘是固定的存储媒介，被封在硬盘里 （除了一个过滤孔，用来平衡空气压力）。
随着发展，可移动硬盘也出现了，而且越来越普及，种类也越来越多.大多数微机上安装的硬盘，由于都采用温切斯特（winchester）技术而被称之为“温切斯特硬盘”，或简称“温盘”。作为计算机系统的数据存储器，容量是硬盘最主要的参数。