What external HD are you using?

I use an OWC Mercury Elite Pro Classic 1TB HDD for Time Machine. I've been using it for a few years now and it's been rock solid; not one single problem with it yet.

I recently purchased an OWC NewerTech Guardian MAXimus 3.0TB "Quad Interface" Hardware RAID-1 (Mirrored) Data Redundant Solution which now houses my ever growing iTunes library.

SandboxGeneral said:

I use an OWC Mercury Elite Pro Classic 1TB HDD for Time Machine. I've been using it for a few years now and it's been rock solid; not one single problem with it yet.

I recently purchased an OWC NewerTech Guardian MAXimus 3.0TB "Quad Interface" Hardware RAID-1 (Mirrored) Data Redundant Solution which now houses my ever growing iTunes library.

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I also have the Guardian Max and it's silent and versatile. I bought mine empty, and it supports Raid 1,0, JBOD, and individual disks if you want to create a Fusion drive

I use a 500GB Seagate for TM (via USB 2.0) and a 2 TB Seagate for my HD videos (via FW). I think a 3 TB HD is overkill for TM. As far a brands, Seagate has treated me well.

Have a LaCie USB3/Thunderbolt series 3T for the TM and a LaCie USB3/Thunderbolt 1T for my movies and pics.. The Thunderbolt TM back up flies...The LaCie 3T does make a faint humming noise but as long as you install it below desk level you don't hear it.. It stops when the iMac is in sleep mode or off..

Have G-Tech Thunderbolt 8 TB which I use for movie and music storage. And a G-Drive 4TB for back ups. Have had one of them for 4 years and works great. G-Tech makes a 3TB as well which you can get at the Apple Store. More expensive than most but are great quality. Built of burnished aluminum and pretty quiet. Don't even notice it most of the time. Have never had any issues with either.

WD My Book Essential 4TB here.
http://www.wd.com/en/products/products.aspx?id=870

Fast Hitachi hd inside and close to silent.

I stay away from USb and have a Pegasus R4 Thunderbolt...Cheap? No. But very fast, and partitioned in 2 RAID0 arrays I can work in real time:

Synology NAS. Works great for TM and wireless (or GigE) too.

3TB Time Capsule for Time Machine
1 TB FreeAgent for CCC

The FreeAgent gets connected and powered only when I want to shoot a CCC backup.

I have a WD my book for mac, 1TB, it is 3 years hold and so far no problems at all but just to be on the safe side I only connect it every 2 weeks when I run my backup, maybe if a drive has to spin everyday all day you might have a shorter expectend life span.

I use the G-Drive 2TB USB 3.0 Great drive!

using a Dlink NAS with two 1TB drives in raid 1 for my important stuff, and for shuttling files around, a few of these Toshiba 1TB USB3. In USB 2 mode, the best I can get is about a 40MB/s write with some other drives, but this little feller will go to 82MB/s on USB3 on my rMBP. Very nice for a 78$ drive! I am using them for my time machine backup, and for backing my bootcamp partition via Winclone.

3TB may be overkill for just Time Machine usage. But that's a matter of personal opinion. If you want 3TB for TM, go for it.

I have a 1TB HDD and a 1TB TM external drive. I have TM backups dating back to August of 2012 on there still, which for me is plenty of backup. My average backup size per day is 200GB.

I'm only using 239GB on my internal HDD since I moved my iTunes library off of it. iTunes is 454GB on a separate RAID array.

If you want to save some money, don't get a Thunderbolt drive just for Time Machine use only. That in my opinion is overkill. But if you will use the drive for video and audio, then Thunderbolt may be more appropriate.

You just have to decide what is right for you and what you're willing to pay for it. There is no right or wrong answer.

Drobo 5D (5x4TB) and Synology DS1512+ (5x3TB).

This is on the Apple Support site. It explains it better than I can, emphasis mine.

Mac Basics: Time Machine

Time Machine is the built-in backup that works with your Mac and an external drive (sold separately) or Time Capsule. Connect the drive, tell Time Machine to use it, and relax. Time Machine automatically backs up your entire Mac, including system files, applications, accounts, preferences, email messages, music, photos, movies, and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of every file, it remembers how your system looked on any given day—so you can revisit your Mac as it appeared in the past. Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month, and weekly backups until your backup drive is full.

Time Machine works best if you use your backup drive only for Time Machine backups. If you keep files on your backup drive, Time Machine won’t backup those files and the space available for Time Machine backups will be reduced.

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You will want a HDD big enough to store a large amount of data. Once the drive is full, TM will delete the oldest backups in order to create newer ones.

PhillyAnt said:

Thanks for that info. So why would someone not want a large drive? If I eventually have 1.5 TB of info on my internal HD, I would probably regret not having a 3TB TM drive, correct? Since it has several copies of all my files, it would take up space a lot faster than just 1 copy of everything. Am I wrong there?

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Yeah, if you have 1.5TB of data, you'll certainly want a drive that can back up the whole thing at least once.

I'm using a 3TB Seagate Backup Plus external hard drive, via USB 3.0 for my Time Machine backup. The speeds are pretty good with it and as far as Disk Speed Test is concerned, it is actually faster at reading and writing than the internal hard drive (the partition without fusion).

PhillyAnt said:

Thanks for that info. So why would someone not want a large drive? If I eventually have 1.5 TB of info on my internal HD, I would probably regret not having a 3TB TM drive, correct? Since it has several copies of all my files, it would take up space a lot faster than just 1 copy of everything. Am I wrong there?

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A 3TB TM drive is the safest and best option for you IMO. It's as simple as that. The price difference isn't that big.

The reason to get a thunderbolt drive for TM is to free up USB 3.0 slots on the back of your mac and have it back up faster. USB 3 is pretty quick though.

I'm actually looking for a TB drive for this very reason but here in Japan I am finding them pretty rare.

Western Digital My Book Studio. Ultra silent. Daisy chained via Firewire. My model (single-drive, Firewire) has been discontinued, but you can still find it on Amazon or other 3rd party stores.

I don't like OWC's Mercury drives, they are very noisy and the status light is very bright.

Warbitrary said:

Western Digital My Book Studio. Ultra silent. Daisy chained via Firewire. My model (single-drive, Firewire) has been discontinued, but you can still find it on Amazon or other 3rd party stores.

I don't like OWC's Mercury drives, they are very noisy and the status light is very bright.

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I have to agree on the status light part! I put a piece of electrical tape over it because it was so bight at night. It would light up the whole room and hallway.

Mine isn't any more noisy than any other HDD. It's quite normal.