Have never used SSD.
From the little I have read about them they seem more expensive than HDD and limited in capacity.
Are they suitable for older systems…?.
Any members using them…?.
Jocklad :-\ 
Yes, I use a Samsung 840 Pro Series 128GB SSD. It’s a vast improvement over the stock 5400rpm spinny drive as to startup time and overall performance on my Lenovo G560 laptop. EVOs are almost as good. I’d stick with Samsung as last I checked, nothing else comes close for the money as far as read/write times go.
Depends what you mean by “older systems” … I gather you won’t get the performance gains over IDE (PATA), but if you’re talking about SATA then it depends on your priorities
SSD = quick, and because it has no moving parts less liable to physical damage if knocked in operation, but has a limited write cycle (so possibly a shorter lifespan)
HDD = cheaper £/GB, higher capacities available, and hasn’t got a limited write cycle (so treated well will probably last longer), but HIGHLY susceptible to damage if knocked (or even suddenly moved) whilst in operation.
On a desktop PC, I suppose the ideal would be to have the OS and apps on an SSD, and also have an HDD for user files/storage
I suppose you could do sommat similar with a laptop, but you’d need an external HDD
So I’m afraid if you’re after a one size fits all answer to that question, or for someone to decide for you, your kinda outa luck 
Not to complicate things, but there are also SSHDs (solid state hybrid drives). These are HDDs, with small SSDs built in for disk caching purposes. These have a high capacity like an ordinary HDD, but an 8/16GB SSD, which the firmware uses as a cache. They don’t have SSD performance, but they are much better than a 5400rpm HDD.
More info - Hybrid drive - Wikipedia
Thanks chemicalfan.
Had never heard of SSHDs (solid state hybrid drives).
Jocklad
Hi, I run a bunch of SSD’s of different types in both workstations, indeed I’ve been doing it so long I now also have a failed drive pool …
Things to be aware of;
o Latency (avg) on a HDD is of the order of 10ms
o Latency (avg) on an SSD is of the order of 0.1ms
Latency is the time it takes to position the drive’s read head and is the thing that has the most impact on day-to-day average performance.
i.e. SSD makes a “massive” difference, although this is generally more noticeable on a server / multi-user system.
[Servers “as a rule” are IO bound, whereas workstations typically lean more towards CPU]
In terms of throughput, older machines will have SATA2 interfaces, whereas newer machines may have SATA3.
- this is pretty critical in terms of being able to get the performance from newer SSD’s.
If you buy a new SSD, if the box doesn’t quote at least 450Mb/sec, move on …
(if the box says “OCZ”, ROFL, then move on …)
However, if you plug a device like this into a SATA2 system, you’ll only see ~ 240Mb/sec from it - as this is the limit of the SATA2 hardware.
So;
o Thruput on HDD is usually 80-160Mb/sec, depending on the age of your system
o Thruput on SSD on SATA2 will be 240Mb/sec
o Thruput on SSD on SATA3 will be 450-550Mb/sec.
Something else you may wish to consider, if you buy (say) 2 x 64Gb drives instead of 1 x 120Gb, you can use LVM to turn the device into a single volume group / logical volume with RAID-0 striping. So LVM will essentially stitch two devices together and present as a single device, reading (effectively) alternate blocks from each device. Using this mechanism I’m getting ~ 850Mb/sec from a pair.
For what it’s worth, this is my device of choice;
Note, the performance for me is good, but it has a very particular feature that interests me. To quote from the spec page;
The THNSNH series also utilises Advanced Power Management (APM) technology to ensure the lowest levels of energy consumption. With an additional ‘data corrupt protection’ feature, the SSDs protect any data which is being moved internally, against unexpected power-loss and write errors.
God damn that drive is cheap! :o
Is it up to spec, I/O wise?
My HP G70 has a samsung 840 pro SSD 240Gb. fitted by me after the original tosh HDD got cooked, and departed this life (!). It is very quick indeed to boot, and read and write of copious photos is fast… no noise - battery life is increased significantly… 5 year warranty… win win win = Highly recommended.
As MP said, above, OCZ are best avoided, I have one - it was “cheap”, is alegedly the same spec as the samsung read/write wise,but… you guessed it… it is rubbish - it even performs poorly as an external drive !!!
Is it up to spec, I/O wise?
If that translates as “does it work as fast as it says on the tin?”, then the answer is “yes” …
- linux kernel 3.12+ has extra stuff to tune for ssd,
in linux you can also tune the IO scheduler, page sizes and mount options.
one of the apps i work with is real heavy on IO, and the ssd is a superb improovment.