Hdd vs ssd

Seen a few posts lately questioning whether an SSD is worth the expense.

In a nutshell - yes!

Whenever I get given a laptop to use for work, if I have to use it, usually one of the first things I do is to clone it to an SSD. The performance boost really is that great.

Below are some benchmarks on my Defiance II. It has a RAID 0 (basically x2) m2 SSD's, a SATA SSD and a SATA HDD inside.

I think the results speak for themselves. ANY SSD is vastly superior in terms of performance to even the fastest HDD.

Just thought I'd put this here as a new post to help reference when the question comes up again.

As you can see, the m2 is up to TEN TIMES faster, and the SATA SSD up to FIVE TIMES faster than the HDD. Granted, this is a size-over-speed HDD but...

I'll add one from my single Samsung SM951 256GB M.2 Drive - if you can stretch that little extra for one of these, it's a must.

It's also worth adding that the lifespan of modern SSDs, and certainly all those you can buy from PCS, are as good as a standard HDD. There is no longer any need to be concerned that your SSD is going to die before any other component. There is still plenty you can do to prolong the life of your SSD (see https://www.pcspecialist.co.uk/forums/showthread.php?14728-SSD-Management) and these things are worth doing, but these days there is no good reason (other than cost) for not having an SSD as your system drive.

SSDs as data drives is a excellent idea if you can afford it but the gains for user data from being on an SSD are much less than that for the operating system and programs. For some types of data, notably music and videos, there is really no gain from an SSD at all.

ubuysa said:

SSDs as data drives is a excellent idea if you can afford it but the gains for user data from being on an SSD are much less than that for the operating system and programs. For some types of data, notably music and videos, there is really no gain from an SSD at all.

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I agree. I have noticed no gains what-so-ever apart from removing that slight 'ticking' noise of the mechanical HDD and having more space inside the PC itself.

ubuysa said:

It's also worth adding that the lifespan of modern SSDs, and certainly all those you can buy from PCS, are as good as a standard HDD. There is no longer any need to be concerned that your SSD is going to die before any other component. There is still plenty you can do to prolong the life of your SSD (see https://www.pcspecialist.co.uk/forums/showthread.php?14728-SSD-Management) and these things are worth doing, but these days there is no good reason (other than cost) for not having an SSD as your system drive.

SSDs as data drives is a excellent idea if you can afford it but the gains for user data from being on an SSD are much less than that for the operating system and programs. For some types of data, notably music and videos, there is really no gain from an SSD at all.

Click to expand...

Don't take this the wrong way, but that is complete nonsense, the second line.

TheGSL said:

Don't take this the wrong way, but that is complete nonsense, the second line.

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Do you mean the second sentence or the second paragraph? I'm happy to justify both of them if you like. I'm intrigued as to why you think one or the other (or both?) to be nonsense?

ubuysa said:

It's also worth adding that the lifespan of modern SSDs, and certainly all those you can buy from PCS, are as good as a standard HDD. There is no longer any need to be concerned that your SSD is going to die before any other component. There is still plenty you can do to prolong the life of your SSD (see https://www.pcspecialist.co.uk/forums/showthread.php?14728-SSD-Management) and these things are worth doing, but these days there is no good reason (other than cost) for not having an SSD as your system drive.

SSDs as data drives is a excellent idea if you can afford it but the gains for user data from being on an SSD are much less than that for the operating system and programs. For some types of data, notably music and videos, there is really no gain from an SSD at all.

Click to expand...

TheGSL said:

Don't take this the wrong way, but that is complete nonsense, the second line.

ubuysa said:

Do you mean the second sentence or the second paragraph? I'm happy to justify both of them if you like. I'm intrigued as to why you think one or the other (or both?) to be nonsense?

Click to expand...

Click to expand...

I've given TheGSL ample time to expand on his/her comment, and explain whether he/she meant the second sentence or the second paragraph. I'll assume that he/she meant the second paragraph so I'll explain why most user data doesn't gain much of a benefit from being on an SSD, and in particular why music and video gain no benefit at all...

Most user data is in very small files, typically less than 1MB (and if you don't believe me take a look at your own user data files). These small sized files are never fragmented (they're too small) and file fragmentation is the killer when looking at HDD performance. What this means is that when read from a hard disk there will be some seek and latency overhead, and the data transfer time from a hard disk is slower than from an SSD, so that the actual time taken to read a typical small user data file into RAM is slower from an HDD than from an SSD. What matters though is whether you can actually see that time difference, so let's look at a 1MB file read from an average hard disk and from an average SSD (both SATA attached)....

From an HDD there is seek + latency + data transfer. For a 7200rpm drive average seek is about 10ms, latency is 4.2ms and the data transfer rate is about 130MB/s which means a 1MB file is transferred in about 8ms. The total read time is thus 10+4.2+8 = 22.2ms.

From an SSD there is zero seek and zero latency, though there is a small setup time (which I'm happy to ignore), the data transfer rate is about 550MB/s which means a 1MB file is transferred in about 2ms.

Clearly 2ms is a lot faster than 22.2ms - 20ms faster to be exact. The issue here though is, can you tell that your file was read 20ms faster from an SSD? The truth is that you simply can't detect a period as short as 20ms (that one fiftieth of a second!), so you don't notice a performance improvement with an SSD with small files, and remember that most of your user data is in small files.

User data that does benefit from being on an SSD is user data that is in large files (and so at risk of fragmentation) and which must be read quickly, high res images are a good example of this type of data. You don't want to wait whilst the screen is painted, you want the entire image displayed in one go.

Music and video gain no benefit from being on an SSD because of the way music and video applications work. In both cases the application creates a read buffer in RAM and the fills that buffer by reading from the disk, only when the buffer is full does the music and video start playing. It is true therefore that a music or video file will start playing earlier if read from an SSD than from an HDD - though again we're talking about milliseconds. Whilst the music or video application is playing the contents of the first buffer it allocates a second buffer in RAM and fills that buffer by reading from the disk. It doesn't matter how long this read operation takes because the application is still playing the contents of the first buffer. Once the end of the first buffer is reached the application seamlessly starts playing from the second buffer. The first buffer is (or should be) released and a third buffer is allocated in RAM and filled by reading from the disk, and so on...

From the above you can see that, apart from the first buffer, it doesn't matter how fast you fill each buffer, the music or video doesn't play any better or any faster, so whilst it's true that music and video files on an SSD will be loaded into the RAM buffers faster you don't notice at all.

As for the second sentence in my OP; 'There is no longer any need to be concerned that your SSD is going to die before any other component' you can easily confirm that for yourself with a web search. A major problem with SSDs however is that when they do fail all the data on there is unrecoverable, in contrast when an HDD fails the data can quite often be recovered...