Solid State Drives (SSDs) do the same job as hard drives (except much faster), but they shouldn’t be treated exactly the same

SSDThere is no doubt that the performance boost offered by SSDs is huge. As far as the content of our drives is concerned (and that includes the operating system, the programs, and the data), we can just enjoy the speed boost and carry on much as we did before.

But the whole technology underlying SSDs is different to hard drives. They are more akin to USB pen drives (“memory sticks”) than hard drives, and this means that there are some things we should take into account.


Do not defragment a SSD. The way that data is stored on them is different to hard drives, so defragmentation won’t help. Worse than that, SSDs only have a finite number of read/write operations before they pack up (don’t worry – a SSD is likely to last longer than the computer it is inside, and longer than a hard drive). Defragmenting a SSD would just needlessly “use up” loads of the available read/write cycles. Modern versions of Windows recognise if you have a SSD installed and don’t attempt to defrag it in the old way. Yes, there is some “disc housekeeping” that Windows performs monthly on SSDs, but we don’t need to worry about it. If that sounds patronising and you’d like to know more about it, then I recommend this article on SSDs by Scott Hanselman. The long and the short of it is – don’t run utilities like Defraggler on a SSD.

Wiping a SSD

Road RunnerOn a hard drive, files are not actually removed when you delete them. They are just marked as “available for over-writing” and the system takes care of overwriting them with new data as and when it feels like it. This means that it is sometimes possible to recover information from a drive that you thought had gone to data heaven. So, there are utilities available (such as Ccleaner’s Drive Wiper) that deliberately overwrite deleted files with meaningless stuff so that the underlying deleted data can not be recovered. SSDs do not work in the same way. When something is deleted then it is deleted from the SSD immediately. Do not attempt to “wipe” deleted data from a SSD.

Operating System

Don’t use a SSD under Windows XP or Windows Vista. It’s not very likely that you would want to do this anyway, but don’t. These old operating systems are not capable of sending the instruction to the SSD (called “trim”) that deletes data in an efficient way. This would eventually mean that the performance of the SSD is badly compromised as redundant data is deleted in an inefficient manner to make way for new data.

Filling It Up

On hard drives, a rule of thumb is that you should never let the drive get more than 90% full as its efficiency will start plunging from that point on. This is because the drive and operating system have to work harder and harder to find somewhere to record (write) new stuff. Something similar happens with SSDs, but here the rule of thumb is not to let the drive get more than 75% full. For some in-depth information on this see Anand Lal Shimpi’s article on filling a SSD.

Speedy GonzalesA Waste of Space

Unless you can get absolutely everything you need on your SSD (and that means Windows, your programs, and all of your data), then don’t waste your SSD by storing large files of infrequently used data on it. Your music files and your videos will not run any more efficiently by being stored on a SSD. Indeed, on my Mac Mini, I have the operating system and programs on a small (120gb) SSD and my entire musc library is stored on a 1tb external drive connected by USB2 (not even USB3). This works perfectly well. OK, it probably means that when I open iTunes my music is not displayed for a fraction of a second, but thereafter it runs just as well as if the drive were an internal hard drive or a SSD.

The same argument might not apply to your photos collection – especially if you do a lot of editing of your photos, or if you often “leaf through” a large number of pictures. There’s no hard and fast rule here, but I would certainly keep anything off the SSD that would push the available free capacity of the SSD down towards the 25% mentioned above (see “Filling it Up”).

SSDs are a big advance on hard drives. No doubt they will eventually be as large as – and then larger than – current hard drives at the same price or cheaper. In the meantime, it’s not surprising that there are some small adjustments needed in our thinking and our practice when using the current generation.

In these days of ransomware, isn’t it dangerous to leave backup drives connected all the time?

Backup Drive on a LaptopVery slowly, data backups are becoming easier to keep up to date. If you buy a Seagate external drive, for instance, it will probably include backup software that you can “set and forget”. Once you’ve made your initial decsions about what you want to back up, how many copies to keep and so on, the software just keeps doing it as long as the backup drive is connected to your computer (usually by USB cable). Yes, it can be a bit inconvenient having an external drive permanently hanging off the side of your machine – especially if it is a laptop that spends a lot of time on a desktop but some time on your lap. It’s just not good practice to forget the drive is attached and yank it around by the cable when moving the laptop! If it goes crashing to the floor then it could easily be “goodnight Vienna” and back to PC World for another one.

That aside, I think a lot of people have actually started to get used to the idea of having backups automatically taken and updated. This is especially true, of course, for Mac owners who just have to set the inbuilt “Time Machine” software to use an external drive and then forget all about it.

And then along comes ransomware. This is malware that encrypts data on your computer and demands a ransom to decrypt it for you. See this previous blog post on CryptoLocker, for instance. There is obviously a very strong argument that says you should never ever give in to blackmail, but if the only alternative is to lose invaluable data then it’s not difficult to see why people pay up. Now, the problem with ransomware is that it can encrypt data that’s on your external drive as well as your internal drive if the external drive is connected at the time that the malware attacks.

On the face of it, then, you are between a rock and a hard place. If you don’t keep your external drive connected you risk losing data that’s not backed up, and if you do keep it connected then the data is backed up but is vulnerable to being snatched away from you by ransomware.

Time Machine Settings

As you can see, I back up my MacBook Pro to a 750gb drive and also to a 1 terabyte drive. This dialog box shows me when I used the drives, so I know which one to use next.

If you’ve got a Mac then it’s actually quite easy to resolve this dilemma. Not only is the inbuilt Time Machine software easy to “set and forget” but it’s also flexible enough to let you use more than one backup drive. So, you simply alternate the drives as often as you wish. If one should fail or be compromised then the other – although probably not completely up to date – will take almost all of the pain out of the situation. This is actually a very good and simple practice. An external drive only costs £40-£60 these days. Just buy another one and alternate them. It’s a no-brainer. For the sake of completeness, I’m just going to mention one more practice that you can adopt if you really want to be responsible about your data backups. And that is to take a second backup onto an external drive and then remove it from the premises. Ask a friend or relative to keep it for you and periodically swap it for a later backup. This may sound like overkill, but it does provide a layer of protection against something disastrous happening not just to your computer, but to the entire location – eg fire, theft, or flood.

To be honest, I don’t know if swapping drives would work when taking continuous, incremental, backups using software such as Acronis or Seagate’s on a Windows PC. It’s just possible that files are marked to say that they’ve been backed up, so wouldn’t get backed up if a different backup drive were substituted. This is almost certainly one of those IT situations where the quickest way to find out is probably to “suck it and see”. In the meantime, you can ensure that a second backup will definitely work by doing a full backup instead of an ongoing incremental one.

Backup Strategy JokeWhether it’s worth bothering about the possibility of falling victim to ransomware is, of course, your own decision. And I should add that, as far as I know, Cryptolocker still only attacks Windows PCs. It’s very difficult to assess the chances of such disasters happening. I recommend that you imagine the situation you’d find yourself in if such a disaster did happen. Go on – really think about what you might lose and how inconvenient it would be. That should then give you some idea of how much effort you are prepared to put into creating and following contingency plans.

© 2011-2015 David Leonard
Computer Support in London
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