thats a fairly pessimistic case, but much closer to real world than the peak throughput numbers of the HD and SSD may suggest. But note that the SSD is still 100x faster than the HDD in that scenario. The SSD will be much much faster still.īoth of those numbers (for 4k) are WAY lower than the maximum SATA2 bus speed. If your IOs are 8k or 64k or whatever just multiply out with that instead of 4k. at 4k each (again, worst case, for comparison to illustrate the point vs. A bit faster if they're larger IOs.ĭue to no moving parts, SSDs can do upwards of 5,000-10,000 totally random IOs per second (some, many many times that under certain inflated number circumstances).
at 4k each IO (worst case scenario - an app is doing lots of small IO operations), that's say 400 kilobytes per second. They can only do maybe 70-100 totally random IOs per second (this is due to the rotational latency for one side of the disc to reach the read/write head, based on 7200pm drives). Much of the IO workload on your mac will be small 4k to 64k sort of size IOs, and randomly accessed across the disk.ĭue to the physical movement required to reach random parts of the hard disk, hard drives SUCK at this. Some basic simplified scenario maths to illustrate. Real world things just don't happen that way. The peak numbers are streaming large continuous file reads or writes or LARGE IO sizes. You can't just look at the peak throughput numbers, because in the real world, a hard drive just won't hit those numbers whereas an SSD will get much closer. Yeah, this is the thing about storage and comparing SSD vs HDD. enjoy the last days of laptops with user-servicable parts :-( Fitting that is a bit harder than the HD, but not bad. Won't speed things up per se but might mean you can get away with just a 256 or even 128GB SSD - most of the speed-up comes from having the system and apps on the SSD. The other thing to consider - if you don't use the optical drive much - is a Data Doubler (or similar) that will let you install a SSD and keep the old HD (for bulky/rarely used/non speed-critical files). With RAM, its worth checking if you need it - MacOS will always grab 3/4 of your free RAM for caching, so you need to look at "memory pressure" and "swap used" in Activity Monitor to see if low memory really is a problem.
I've used both a Crucial MX100 and Sandisk Ultra II in my "backup" Mid 2010 13" MBP (Whenever I need the "backup" Mac, I panic-buy a SSD to make it usable - then after a few months I steal the SSD for another project and put the old HD back in.)įitting is an absolute doddle, but I second the motion to make sure you have the right screwdrivers. As others have said, though, its not worth paying a fortune for a super-fast model for an old machine (although you don't need to hunt down an old SATA-2 drive). SSD is still the best bet for giving your machine a new lease of life.
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