In another post (thread 37181), joemike noted: “…Apple does not recommend putting the Time Machine backups on a drive with any other files. Not even if you put the Time Machine data set in a separate partition.”

That caught my attention as I thought partitions were inviolate. And if they are not inviolate, can it also be that different volumes are likewise not inviolate?

And to make matters worse, is the answer dependent on whether the drive is spinning or SSD?

Clearly, I am confused. So please, any info/clarification will be appreciated.

They are. The information on one partition doesn't know or care what's on another.

I suspect the reasoning is more about backup reliability and speed, and less about any kind of problem with combining Time Machine data and other data.

Backup reliability: Backup storage devices should not be used for day to day operations, or they may fail when you need them most. hey should be used as little as possible to maximize their lifespan.

Speed: If you are reading from or writing to the TM drive while a TM backup is running, that may impact the speed of the backup, even if you're reading from or writing to a different partition on the drive.

Many thanks, Tacit. Good info, indeed. Though it does seem odd that speed and/or reliability would be affected to the extent that caution is called for. To me, it smacks of the rationale that if you don't use your drive it will last longer and be more relaible.

Here is joemike's response to your question.

Thanks, Artie.

I may be beginning to understand and appreciate the nuances here, but only with respect to SSDs (I still don't see the problem with spinning drives).

I don't doubt the counsel is sound, it's only that I would be uncomfortable explaining all this to others. And to me, that is a clue is clue that my understanding ain't really what it ought to be...

Really? I had originally thought about tacking my question onto Pendragon's thread until I realized my question wasn't the same. I ask about adding files to a Time Machine drive without being in a separate partition. i.e. the Time Machine data and the other files are in the same partition. I assumed that, without the barrier of a partition, the problem might be more serious.

Quoting ryck: "Really?"

Actually, joemike's post in your thread doesn't specifically deal with your question; it only specifically addresses your intro, which is more or less Harv's question.




On the other hand, though, tacit has specifically addressed your question in this thread...

Unless I'm mistaken, Harv, you've got a nomenclature issue going there: a partition is a volume.

Edit:
I don't follow your differentiation between SSDs and HDDs as respects the issue.

As far as Time Machine or OS X (and the same is true for Windows, Ubuntu, Unix, etc.) is concerned they see exactly the same logical drive regardless of whether the drive is a rotating media HD or an SSD. The intelligence/firmware in the drive itself is specifically designed to make the physical layout of data on the drive as well as the actual storage media invisible to the operating system and therefore to applications. That is the principal function of the IDE/PATA/SATA interface.

The OS views Fusion Drives and even multi-drive RAID arrays as having the same logical structure as a single HD or SSD but there is an additional layer of abstraction either in software or hardware required to make that happen.

That explanation, joemike, helped a lot. Progress has been made.

In a way, this reminds me of quantum physics-- I understand it (pretty much, sorta) when working at it. But should I return to the issue in a few weeks, a cerebral restart is required.

Not sure if splitting hairs here or if I'm using it wrong, but I've always assumed a volume is a data partition, like one formatted HFS/NTFS/FAT32. Other types could be "Free", "drivers", etc. OS 9 had typically around 9 different partitions on any given drive, only one was the Macintosh HD. The others were the drivers needed for the older machines to boot the drive. Macintosh HD may be on partition disk0s8 for example. Also, technically, the entire device is a partition too. It's the first partition on the drive, which describes itself.