Card slot -TM backup, extra storage etc?

[macstatic]

I haven't actually used the SD card slot in my mid-2012 MBP more than a couple of times but recently read about how some people use it as a sort of SSD drive.
I'm definitely going to replace the internal HDD with an SSD at some stage, but as it's not within my budget the SD card slot gave me some ideas.....

1) as an SSD with OSX and the apps on, then use the whole HDD for file storage.
2) as a Time Machine backup drive. This would be VERY useful IMHO as the drive would always be there (as opposed to attaching an external drive which is often forgotten, hence no regular backups)
3) as a smaller SSD when a real SSD can't be afforded. Not sure how much space OSX needs, and haven't checked SD card prices lately, but a relatively small/low costing SD card might be enough to hold OSX and the apps
4) a clone of the HDD (at least of OSX and the apps) -just in case the HDD stopped working and you'd at least have the ability to use the computer

So I'm wondering how an SD card compares to an SSD when it comes to speed, data integrity and if it "wears out" quicker than an SSD?

 

[keysofanxiety]

SD cards are terribly slow and you just wouldn't see the performance benefit if you had the OS on there. If anything it would actually be slower than your 5400RPM drive ...

Honestly you'd just be better saving up for an SSD and replacing the HDD with that. Plus if you get a USB SATA dock, you can use the old HDD as your Time Machine backup.

 

[JTToft]

(1), (2), and (3) are bad ideas for the reasons stated above. SD cards are slow and not nearly reliable enough for mission critical use. (4) might be OK as a last resort, but not as your primary backup or anything to rely upon.

Good SSDs in the smaller ~120 GB capacities can be had for all the way down to about $30 nowadays. If you're tight on money, the Kingston V300 is a decent option.
http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias=aps&field-keywords=120+gb+ssd

 

[macstatic]

I didn't know that about SD cards -being a poor SSD replacement I mean.
Are they unreliable in general (for cameras etc. as well) or mainly in this particular setting (where with computers there's a LOT of read/write cycles all the time). Are SD cards less reliable than other memory cards (CF, Memory stick etc.) or are they generally just better suited for less challenging stuff other than with computers?

I also didn't know SSD prices had dropped so much. The problem is that if I buy a cheap SSD now I'll get lots less storage than with my existing 500 GB HDD but perhaps it's enough for the most part -and I can put the HDD in an external case for additional storage if needed.

I know a lot of people replace their laptop optical drive (CD/DVD) with a second drive, such as described here, which would probably be ideal for a combination of a large HDD for file storage and a fast, smaller SSD for apps and OSX, or as a dedicated Time Machine drive, but personally I prefer having an optical drive in a laptop for verastility when travelling. You never know when you come across a CD or DVD, although I see it's been a while since I last burnt a CD or DVD.

Keysofanxiety: USB drive docks are a great idea -not only for my Macbook Pro but also as external backups and additional removable storage for my Mac Pro. Would you recommend having one with USB 3, Firewire 800 or eSata or a combination of interface options? I actually have a rack mounted 4-bay drive dock connected to my Mac Pro but it has a 2TB drive limit and you need to mount the drives on trays. It also has noisy fans. I assume those USB docks you mention might not even need a fan because the drives are better ventilated (mostly not inside an enclosure)?