Most commonly used backup methods
Hello and welcome to my User Tip.
Can't stress enough the importance of backing up your personal data off the computer.
Computer repair folks can replace the operating system and most of your programs, but your user files are unique to you and once the medium they are on is broken, lost, stolen or destroyed, your data on them is gone.
Follow these rules of backing up your data
#1 Rule. Whenever affecting changes to the drive in Disk Utility or other like software, make sure you have backups of all the data of all the partitions of the entire drive being affected and disconnect all other non-relevant drives (especially TimeMachine) to avoid mistakes and background automatic updates.
#2 Rule. Maintain two backups of your data on separate hardware at all times.
#3 Rule. Have at least one of those backups off site to protect against theft, fire, hackers, malware, estranged persons etc.
#4 Rule. Have your most valuable data burned to cd/dvd's archived/dated periodically offsite in case of slow creep issues and malware. Burned non-rewriteable cd/dvd's are naturally malware proof as they can't be changed later unlike other rewriteable media.
What is your personal data and where is it stored?
The contents of your User(s): Music, Pictures, Documents, Movies, Desktop etc., folders.
The "User"/Library folder (hidden in 10.7+) contains certain settings, caches, specific program file and preferences tailored for that user account. It's inside the User folder, invisible and copied if you copy the entire User home folder, however I don't advise restoring this back unless your positive it's free of corruption/issues.
Basic emergency quick copy method
Connect a new self powered external storage drive, ignore the TimeMachine window that appears if it does, say no. It will take too long and if your having problems, will cause more as you don't want to make a TM backup of corrupt data that will fail to restore later.
If you just got a new drive and some of your large files (like over 4GB) are not copying over, then you need to start over and format the drive in Disk Utility > GUID with OS X Extended Journaled or right click format the drive exFAT on a Windows PC (XP needs a download from Microsoft) but do not format it MBR exFAT on a Mac if you want to connect it to a PC later as the Mac exFAT fromatting has issues.
In the Finder click the Go menu and select Computer, open your boot drive and then open the Users folder and copy to the external drive with enough space for all your personal files.
Once the copy is completed, drag the external hard disk icon to the Trash can to unmount and then physically disconnect the drive.
I recommend this step be taken in addition to a clone or TimeMachine drive if you already have one.
The solution for "You need to free up space on the startup disk"
These are drives that are basically containers for your extra user data held in more or less a permanent fashion until you delete it. So the point with these is if you are running out of room on your boot drive, you can use a storage drive to keep extra stuff you don't want to delete, but don't want to keep on the boot drive and thus eventually deleted on the Clone or TM drive as those are copies of the boot drive and eventually updated to reflect the boot drive contents.
If your here because of "You need to free up space on the startup disk", my advice is to look in your iTunes for any content (perhaps subscriptions) that have gone out of bounds. Next look at the Movies folder as a great source of large files to move to a external drive. As you know, moving requires copying the files to the storage drive and then deleting the originals on the boot drive to free up room, then reboot the computer when finished just to make sure OS X understands it has more free space available now.
Use your Applications/Utilities/Activity Monitor program to see a pie chart of your drive space, keep it ideally 50% free, but never more than 80-90%!
Once you have some room, download this neat free program that will determine what other files are taking the most room on your drive. Some you have control over, others you won't as they belong to OS X, so let it give you a idea of how to better manage your boot drive space.
Remember sticking with the rules of backup to also have another hardware copy of your storage drives data as well on another piece of hardware. Since your data will be off the boot drive and eventually off the backup drive (clone or TM) then you really only have one copy on the storage drive! Don't drop it!
TimeMachine has the ability to backup other drives as well as the boot drive, I DO NOT recommend you do this because what happens if the TimeMachine drive fails? Remember don't keep many software backup eggs in one hardware basket! 🙂
Most drives come formatted FAT32 (MSDOS) which work with Mac's and PC's, however if ANY of your files are over 4GB in size you need to change that drive format to exFAT in Disk Utility (all data on the drive will be erase during formatting). If you choose OS X Extended-J (or any Apple format) the drive can't work with a Windows PC without additional paid software. IMO, keep your drive access options fully open with MBR or GUID & FAT/exFAT with storage drives.
Read more here:
Will not boot after seeing "You need to free up space on the startup disk"
Your going to need to follow the steps in the Data Recovery Efforts Explained to access your internal drive either via a bootable clone, OS X installed on a external drive, or via another Mac using FireWire Target Disk mode to access the internal drive and remove files.
Try holding the Shift key down while booting, that can hopefully avoid the process of creating and booting from a data recovery drive.
Important Tip: Use your Activity Monitor in your Utilities folder and keep your boot drive (for best performance for hard drives below 50% filled) not more than 80% filled for any drive.
Note for the experimenters: One can't simply copy OS X and everything to a storage drive and expect it to boot, it has to be cloned (or installed), or imaged by Disk Utility so it does special things to allow the computer to be able to boot from the drive
Don't put all your software backup eggs into one hardware basket!!
Although external drives come in huge capacities, there might be the temptation to partition them and have say TimeMachine on one and a bootable clone on the other. Or place all one's machines backups/data on one drive.
The dangers with this is, if the hard drive fails mechanically or electronically, then all your backups are gone.
Have multiple copies of your personal data on separate hardware, in separate locations, using different means and maintain two copies of your personal data at all times.
Also never trust your only copy of valuable content to rewritable media, burn cd/dvd's for permanent storage and store offsite in a safe location.
One needs to protect their personal files from not only software problems, but hardware, theft, fire and other disaster as well. Think, if a thief breaks into your house and takes your iMac, they will also likely take the connected TimeMachine drive as well.
Also consider the possibility that you might not have the ability, funds or your needs will change to buy a particular brand the next time around, so keep your files and data in as easily accessible state as possible.
For instance, most graphics formats are interchangeable, most basic text formats are as well, but once you start creating or saving data into a certain restrictive way like a program that creates files that only runs on one platform, makes it very hard, if not impossible, to use it anywhere else with anything else. Try to keep you data and backup options open, so files can be accessed regardless of platform, backup, operating system or program as much as possible.
When you choose to decide to use software, check to see if they also make a version for other operating systems. Your job may require you use Windows when you use a Mac at home for instance. So having your files in a format that can be used by either platform is ideal.
Whole boot drive rotational backup + saved states
With a external drive combined with built in free software in OS X on the Mac, will image your entire current boot drive/partition in a rotating in time state fashion. It allows you to undelete files you have perhaps accidentally deleted. It will also allow you to restore your entire boot drive/partition less it dies from mechanical failure. However TM only restores, it won't boot or run your computer like before, only boot to restore in the more recent versions.
The advantages of TM is it's automatic nature, the more new to computer user like friendliness and simplicity.
If your new to backing up your data, simply connect a blank external hard drive larger than the internal boot drive and TM will popup and ask you to make it one, allow it and let it go, it will take some time as it has to copy everything and format the drive first.
If your new to backups, then use Apple's TimeMachine right away, something is better than nothing and TM works well for most.
One can learn more in depth detail about TM and it's other options here:
Have a portable Mac and using TimeMachine?
You might have noticed some substantial drive space going to "Backups" on your boot drive. This is so you can use TimeMachine to restore deleted files while not physically connected to the external TimeMachine drive.
If you don't want this taking up extra space on your boot drive and not prone to accidentally deleting files, or for more security reasons you want you delete stays deleted.
Then enter this into Terminal program: sudo tmutil disablelocal and entering your Admin password, then reboot to see the changes.
To re-enable it: sudo tmutil enablelocal
Some mistakes made with TimeMachine
If you have a "You need to free up space on the startup disk" problem and connect a drive and it asks to make a TimeMachine drive, that won't solve your problem, as it's only a backup method and won't free up space on your boot drive.
Say "no" and drop down later in this Tip to "Storage Drive". You can make a TimeMachine drive later on another drive when you have resolved your primary issue to avoid copying corrupted data.
Assuming TimeMachine doesn't delete data, it does.
TimeMachine is NOT a permanent storage drive, eventually or by large changes the TimeMachine saved states can change and thus your older saved states with files will be gone.
"I'm sick over the loss of my pictures, but I've accepted there is nothing I can do at this point. I'm trying to make sure it doesn't happen again. I feel like I trusted Time Machine and it let me down, but that might be because I thought it was doing something that it really wasn't."
If you want a permanent, archived version bootable state of your OS X boot partition, then you need to look at making a bootable clone image on another external drive, use TimeMachine for more immediate uses and restores.
Assuming TimeMachine will always restore any/all data, it doesn't.
I don't advise making a TimeMachine drive if your experiencing problems with your machine, quickly copy just the Users file folders off the machine to a storage drive as soon as possible as your boot drive may be dying and the TM will take too long to setup or copy corrupted data.
If TM is your only backup, don't be too quick to erase the internal boot drive (and thus your only other copy of data) if OS X is refusing to boot.
Rather attempt to fix in place: ..Step by Step to fix your Mac
Or attempt to recover a extra copy of your data off the boot drive first: .Create a data recovery/undelete external boot drive
One can't easily verify if the data on the TimeMachine drive will restore properly or not if and when you do have a problem with the internal boot drive. TimeMachine is a backup only, it's not bootable to confirm reliability to restore, thus it backs up corruption unawares just as easily as it does the good stuff.
Many people have erased their only copy of their data off a boot drive thinking TM will restore, only to have it also corrupted and fail to restore.
TM drives also have none or limited booting to restore-only capability so they force you to get your Mac's internal drive immediately repaired, which you may not be in the condition to do so.
Apple says I can backup multiple drives with TimeMachine?
What about partitioning a TimeMachine drive and using the extra space for storage etc?
Yes you can do this and it has this option, but in the interest of best preservation of your data it's best you DON'T do these two things.
What people tend to forget is hardware fails just as often as software, you drop one drive with many backups on it, or it gets it stolen, power surge or major glitch and it takes all your backups with it. Never place all your software eggs in one hardware basket.
With TimeMachine there really isn't a easy way to verify the files were written to the drive, you can't open them directly from TimeMachine drive to verify.
People have reported here of TimeMachine NOT backing up their files, restoring and not finding their data. Why? Who knows?
TimeMachine stores "states" of your boot drive, so it needs more drive space than what's on your boot drive to save those multiple states.
Your data tends to grow, on your boot drive and on your backups, so you need to have space to expand into.
Consider the case of malware, if it has write ability to your drives, it's going to infect everything you have physically connected. Your going to wish you had your data on drives that were never connected to the infected system once you realize the malware erased it all.
The best advice is to have a multiple backup system and match each piece of hardware with two of it's own separate hardware backups.
So if you have a boot drive, you need two external backups of it on separate hardware.
If you have a storage drive for extra space, then you need two more drives as backup of that on separate hardware.
For essential files, burn a naturally write protected cd/dvd's occasionally and store offsite in a safe place.
This offers maximum protection against both software and hardware issues occurring, as well as acts of God, criminality, fire, power surge, lightening strikes etc.
Drives are cheap, data is not. Do not place many software eggs in one hardware basket.
Whole drive bootable clones + optional saved states
These are my favorite and the choice of "power users". They are simply clones of your OS X partitions which you can make to another blank drive (or partition) and hold the option key and boot from them (if they have OS X on it of course).
When booting a Mac, if you hold the option key down (wired or built in keyboard) it launches Startup Manager, which allows one to choose a alternate boot option.
Some of the things one can do with a cloned boot drive:
You can hold the option key and boot from them and use the same computer like before in nearly all cases
You can use them to access data on a non-booting internal drive for data rescue operations
You can use them to repair the internal drive
You can erase and reverse clone, run data recovery software and anything else just about.
You can even clone the clone to another computer of the same make/model/year or to another external drive or partition.
You CAN'T clone a OS X boot partition/drive to a different model of Mac in many cases), but you can use Migration Assistant on a clone to a new machine.
You can access the data on a clone directly, from any computer (Mac, Linux or Windows) that can read the Mac drive format. Windows only needs MacDrive installed to read the Mac's HFS+ drive format.
You can clone your OS X partition to a larger drive before switching them using a external drive or using a IDE/SATA to USB adapter cable for a removed internal drive.
Your data is not trapped, you can copy it and do anything just like any other drive, except only boot with it to the same Mac or like it.
You can set them to auto-update on a schedule, have as many as you need, some spaced back in time too, use them for testing.
You can (like what I do) auto-clone one partition to another on the same boot drive every other day, just in case you do delete something you have a couple of days to get it back.
You can also clone non booting drives too.
You can run Apple's Migration or Setup Assistant against a OS X clone to transfer Users etc., to a new machine.
Also you know those times when a recent OS X update just won't work with that third party software you need like right NOW! and can't afford to wait for a update? Well if you made a recent update of the clone BEFORE applying a OS X update, then you could simply option boot off the clone drive. How to clone your boot drive: https://discussions.apple.com/docs/DOC-6101
Clones are considered a more advanced option and you'll likely not get much in the way of user support from Apple as it's not software they make or service, however they use cloning software themselves, nearly everyone in IT tech repair /data recovery does.
There is just some restrictions, no Filevault and you can boot the clone only from the same make/model/year of machine in most cases.
The first clone does everything, and like the first TimeMachine backup it takes the longest, updates to either afterwards are shorter as only the changes are saved. Carbon Copy Cloner has a host of advanced scheduling and backup options and features to tailor the cloning/backup process to your needs, unlike TimeMachine.
Newer iMac's (2011+) have Apple installed software deep on the drives that needs to talk to the OS to settle down the fans, if your internal drive is mechanically dead and your booted from a external clone, it's likely the fans will race. So since one should be getting their internal drive replaced shortly anyway, a external clone is a emergency boot option in this case.
To make a clone of your OS X boot drive/partition
Disk Utility: Click the whole drive then Partition Tab, then Partition: 1, click the box, Option: GUID, Format: OS X Extended Journaled. All data is lost on the drive when formatting.
Simply download Carbon Copy Cloner and select your boot partition and clone it to a blank powered external drive using the default settings for the first clone.
Hold the option/alt key (wired/built in keyboard) and boot from it to check it out. The default clone settings are fine, after that it updates and backups up the changes, so you will need to control that if you want to maintain a pure clone.
CCC will also clone the Recovery HD for restoration to a blank internal drive on a Mac (like that has no Internet Recovery built into the firmware or is on a later OS X version), a added bonus.
Note: I get no compensation for product mentions, I just use what works best for everyone.
Another popular cloning software is SuperDuper, however it doesn't copy the Recovery HD partition, a separate process of creating a Recovery USB is required, then use that to set up a new drive, then boot from the clone and clone OS X to the OS X partition on the new drive.
Another method is to use Disk Utility and make a clone, however it only works on one partition at a time, does the whole thing and no update or scheduling ability. So it can't do the boot volume and Recovery HD at the same time like CCC can.
If you upgrade say OS X 10.7 machine (10.7 from the factory) to 10.8, the Internet Recovery is for 10.7, and the Recovery HD is for 10.8. So CCC works well for this so you get a copy of 10.8's Recovery HD.
If you need to clone Windows/Bootcamp via OS X then checkout WinClone at MacUpdate.com
I haven't used this, so find out the details, if you need to recreate the Bootcamp partition, will it "notify" Windows that it's in a new partition/size etc.
Windows takes the hardware id information into the copy protection scheme, so when you clone Windows back onto a new internal drive for instance, you will have to re-validate Windows with Microsoft.
TimeMachine vs bootable clones FIGHT? Not.
TimeMachine has it's advantages and disadvantages, bootable clones have theirs too. They are two different backup methods with some overlaps, to be complete and through you should have both methods employed as relying upon only one sole backup is not good.
TimeMachine is a backup system, there isn't a easy way to check that it's restore function is going to work if the time comes, however it only takes a few seconds to boot off the clone drive to determine if it's good or not.
TimeMachine is better for the shorter term, more frequent updates and closer to the machine at all times and bootable clones are better for more advanced options, hardware protection (gets the machine up again fast) and longer periods between updates, saving a bootable clone offsite someplace safely.
If your location gets burglarized, the thieves will likely take your always connected TimeMachine drive with your computer. The clone offsite will save you depending when it was last updated. Most files restored is better than nothing.
If your hard drive dies, the TimeMachine drive won't assist as it's not bootable. A clone is bootable and will get up and running again in seconds.
If you get malware, it likely will infect you TM drive as it's connected more often, but a clone gets connected less often usually, so it will tend to be safer.
With clones, the drive is completely accessible from any computer (Mac, Windows with MacDrive, or a Linux PC) to grab any file(s) at any time.
However with TimeMachine the software run only on recent Mac's. So your data is trapped basically, accessing the drive directly is extremely difficult and if a Time Machine drive gets corrupted, it's quite a mess to recover your data out if it or to a older Mac or non-Apple computer. The right thing for Apple to do is create TimeMachine software for Windows PC's as you may not be able to buy a new Mac the next time around, or require a Windows PC for a job, now your files are trapped. So think clone as a rather large basket of salvation for many situations.
Bootable clones have saved MANY peoples bacon, I kid you not. However some backup with TimeMachine is better than No backup.
Computer newbies tend to use TimeMachine exclusively for the undelete ability mostly.
Seasoned users may use both. More seasoned users may have multiple clones only, even also a partitioned boot drive that auto-clones A to B at certain periods
Cloud based storage
Although some may take the time to store great deals of information with cloud based services, your ISP which connects you to the Internet tends to reduce your upload speed to a fraction of your download speed. So it makes this impractical as a backup all but for small uses on a constant basis. There also is a privacy and security risk with data stored with online services. It also requires the Internet for access, which may or not be available. The advantages is syncing data across devices and places, offers another solution to keeps one's user files. I would keep online backups restricted to users files because much more than that is simply going to take a long time to complete if it ever does.
Here is a one good reason not to rely upon iCloud
The potential problems with Cloud storage are unnecessary risks for little gain in return compared to local storage you control. Hackers can alter your data, setting you up, RIAA deciding you don't own the music files you uploaded from your cd rips, or law enforcement looking at your files and using them as incomplete and inaccurate evidence. No warrant needed to search the cloud, they can do it anytime they like. Unlike local storage in your home, office or safe deposit box that does require a warrant.
“I really worry about everything going into the cloud,” (Steve) Wozniak said, according to wire service AFP. “With the cloud, you don't own anything. You already signed it away.”
In the end, he added, it all comes down to control: “I say the more we transfer everything onto the Web, onto the cloud, the less we're going to have control over it.”
If you insist on using the cloud, also make local backups as you will need them. Eventually you'll realize that time is wasted uploading to cloud storage and just another consumer fad with no basis in practicality. Servers have stored data for ages, there is a time, purpose and place for them that really doesn't jive well with most consumers use of their machines.
CD's, DVD's and BlueRay disks (permanent, archival)
Don't hold much as storage drives, but these are permanently burned (some are rewriteable) physical copies of your data on disks that can be stored or send one way in a physical fashion. The Mac can't play, read or write BlueRay at this time, however external options are available.
AudioCD's can be created in iTunes for playback on audio cd players, this doesn't make a good backup method for music.
MP3 CD's and DVD's can be created in iTunes with MP3 audio files (iTunes Store Music has to be copied and converted from AAC) and played on devices like MP3 CD players, a lot of vehicles can play that. And some DVD players can play MP3 DVD's.
DataDVD's and CD's can be created in iTunes (if so contain all the song info) for backup, or in the Mac's Finder for making a backup of other personal files like pictures, movies etc.
To burn video DVD's, one needs special software to take the finished movie product and convert that into a format that the DVD player can read.
If you value your data, in addition to making clones, storage drives and TM, that you also make DataCD's and DVD's label and date them and keep in a very super safe offsite location, every 6 months or sooner intervals depending how much you buy or generate. This is because of theft, burglary, fire, natural disaster, electrical problems, hackers etc. Also because of slow creep issues, you might not have realized that a portion of your music or files might have gotten corrupted and your going to thank yourself that you made archived versions.
Your going to likely go to the office or computer store to buy CD's and DVD's and realize there are two formats, CD+R, DVD+R and CD-R, DVD-R, both should work on most recent Mac's and other devices. It used to be that some machines only supported one format or the other, so if you have older machines it's best to check first.
CD-RW/CD+RW and DVD-RW /DVD+RW are basically rewriteable, so one can erase them in Disk Utility a few times and use them again.
Note: if you see DL on the disks, it's means it's a Dual Layer, meaning it can burn twice as much on one side. There are also Dual Sided disks and Dual Sided/Dual Layer disks too for maximum data capacity. Most Mac's now all have dual layer disk burning capacity.
Note that Mac's are finicky when it comes to their CD's and DVD's, buy the small pack and try some out (or borrow some) and see what works good with your Mac before buying the big case. Also try to never put back a CD or DVD into the new container, once you take it out consider it used and place it in with other used media with a plastic case to protect it. The underside of the CD/DVD is prone to damage, so don't touch it or place the disk down on a hard or dirty surface. A soft clean cloth or back in the plastic case where it's elevated by the hole in the center where you should be handing the disk or by the edges.
Other disk tips:
If you need to clean a cd/dvd, use a tiny bit of rubbing alcohol to cut the oils and dirt and wipe/polish to a shine.
Don't place the bottom of the cd into contact with anything that can scratch, dirty or mar it's bottom area, including your fingers as they contain skin oils, use a case when not in use.
Don't stick a cd mini into a slot loading Mac, it's not designed for that and will get stuck in there, use the standard size disks only.
USB thumb/flash memory drives:
These are smaller flash (not Flash the web browser plug-in) memory based USB port powered storage drives used quite commonly for transferring files between computers. They are usually formatted with a MBR and FAT32 automatically at the factory so both Mac's and PC's can use them and exchange files.
It's possible to change the format on them to GUID and OS X Extended (Journaled) and install OS X onto it, or copy your Recovery HD to it (if running 10.7+)
Warning! USB thumb drives wear out and are easily lost or tossed in the wash, so do not depend upon them for permanent uses.
Also because they don't have a label on them, you can't tell what's on them before connecting to a machine, and thus infecting your computer with malware.
Port powered vs self powered backup drives
Port powered devices sometimes can draw more power and the Mac can shut it off, meaning your backups might not occur or if they do, they can get corrupted as the backup doesn't finish.
So ideally, please use self powered drives for backups over port powered, or if you can't help but need a port powered, also use self powered as a additional backup and a powered USB hub.
Smaller port powered drives should be used as temporary transfer drives, not as permanent storage.
Choose carefully about enabling Filevault
Warning!: Filevault 1 & 2 are CRACKED, there is $1000 third party software that can gain access to your encrypted files, it's likely been reverse engineered by now for any petty data thief to use.
Filevault is great way to encrypt all your contents of your drive, supposedly so if you lose your Mac the data can't be recovered.
That's great and all, but it also stops any data recovery or repair efforts on non-working drives/partitions because the same means to recover your data or replace a certain buggy file to get your machine working again are also used to spy on your stolen/lost computer. Filevault can also slow down the performance of your Mac as the CPU is busy encrypting and decrypting everything back and forth to the storage drive.
Also you need to have the room on the startup hard drive to be able to send the newly encrypted data too, it obviously can't write to the same spot on the drive that contains your unencrypted data until it's finished.
If your going to choose performance robbing Filevault, please do so when you first setup the machine (or "fresh install") if all possible, or suffer later when try to create Bootcamp partitions etc which need a nice large space at the bottom of the drive.
In other words as time passes and your hard drive fills up with data (and other User accounts), the harder and more problematic to enable Filevault and the more trouble you will have.
Filevault isn't exactly private, the password will be required to repair your machine if it suddenly doesn't work or by law enforcement, customs etc.
You may want to consider using a alternate encryption method than Filevault to better suit your needs, which Filevault is more for government and corporate types than for most ordinary folks with only a folder or two of data they want to remain private.
So I don't advise using Filevault for most users, it only complicates recovery efforts.
Other secure storage options
Just encrypt a single folder of files, software can do this. What makes this a great option is data recovery/repair efforts can commence, the encrypted files transferred to another machine and with the right password and software they can be accessed. This is more likely the better option for most users of computers due to their ability to be easily transferred like any other file.
Self encrypting external storage drives. These contain their own hardware based encryption, a keypad and/or a key to allow access to the files. Use with any computer that can read the decrypted files. No software running on the computer means more security and stability. Good for large scale portability of lots of encrypted files, like in medical field http://www.datalocker.com/products/datalocker-dl3.html
Self encrypting USB thumb drives, Iron Key, smaller storage, portability and easily disposed. Good for going back and forth from work sharing files between home and office. BEST OPTION.
Disk Utility encrypted image, Open Disk Utility and click on "New Image" a window appears to create the size and encryption method.
Secure deletion methods
Due to hidden databases Apple maintains on more recent versions of OS X, and many new Mac's coming with SSD's and Fusion hybrid drives with flash memory, if you have secure erase needs it's best to remove and retain physical control over the storage in your machine if posssible or allowed.
Only some older Mac's can the storage be upgraded or removed by the user, newer Mac's are nealry all sealed up and non-user accessible.
In other words if you have sensitive data you don't want anyone to see, your machine is broken and needs repair, if you can't self remove the storage yourself, then don't take the machine in for service period.
The NSA approved method for secure destruction of sensitive data on any solid state storage is grinding it up into a fine powder.
Keep your sensitive files off the Mac onto a external drive and don't include it in TimeMachine backups. Secure erase data on a Solid State Drive? https://discussions.apple.com/docs/DOC-5521
Recommended formatting reading
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