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How does an SSD compare to say 5 80gb Sata Drives in Raid 5?

SSD IS an SATA drive...
i think you meant spindle drives (which are also SATA drives, just like SSD)

there are 5 significant metrics:
Sequential Read
Sequential Write
Random Read
Random Write
IOPS

Anyways, it depends on the RAID5 implementation, most have very poor performance. (motherboard based often is worse then a single drive)
An amazingly good RAID5 controller (those are expensive, ~300$+) of an array of N drives will give you performance of (N-1)*performance of one drive.

An SSD tends to be 2-3x the sequential speed of a spindle drive, and ~100x the random read/write speed of a spindle drive.
The SSD will still annihilate the spindle drive RAID5 array. You get a mix of random and sequential usage on your computer; it isn't that random speed is more important than sequential, but that the sheer magnitude of the difference in random speeds between SSD and spindle drives (100x) makes all the difference.

Keep in mind that you are capable of using a RAID0 array for better performance than RAID5, even on cheap controller. Even the cheapest controllers should have a performance of N*speed of one drive on a raid0 array of N drives.

And also keep in mind that nothing is stopping you from using multiple SSDs in RAID.
 
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Taltamir is right, for random reads and writes SSDs are the nuclear option. However, for sequential disk I/O they're effectively the same. And RAID5 with a bunch of old slow disks will never approach an SSD for any operation.
 
HardOCP did a RAID review with 4 1gb platter drives on the Mobo in my sig and for large Throughput tasks it blew away SSD. I don't recall how it did for other tasks, but really when it comes down to it moving hundreds of gigs of data just doesn't matter to the average User.
 
sandorski said:
HardOCP did a RAID review with 4 1gb platter drives on the Mobo in my sig and for large Throughput tasks it blew away SSD. I don't recall how it did for other tasks, but really when it comes down to it moving hundreds of gigs of data just doesn't matter to the average User.
Click to expand...

Large throughput = sequential reads... the best spindle disks get 120MB/s sequential read. While a normal result for a gen2 SSD is 200 MB/s to 250MB/s
Assuming raid0 for best performance you get 4x120 = 480 MB/s
That is going from the SSD being 2x faster in sequential performance to the raid array being about 2x in sequential... But the SSD is still hundreds of times faster in random writes and reads.

In actual use a single generation 2 SSD (excluding the samsung and jmicron ones of course) will still demolish that RAID0 of 4 spindle drives
 
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Yeah, at this point the big thing stopping me from switching from RAID is price - a 250GB (which is what I would need) is still too high for my liking. PLus a new generation of drives is about to come out.
 
Dadofamunky said:
Yeah, at this point the big thing stopping me from switching from RAID is price - a 250GB (which is what I would need) is still too high for my liking. PLus a new generation of drives is about to come out.
Click to expand...

I was worried about this too, and ending up blowing more money than I had intended to on my newer rig which is still very budget limited.

Vertex 2 90GB SSD was on sale for $149, coupled with a VelociRaptor. I use the SSD for OS and software and the VelociRaptor for games. Then have a 2gb for storage. Works very well.
 
I used to run 4x160GB raptors (last gen 3.5" ones, dell oem SATA 2 w/ncq/etc) in a big raid0 stripe. (Kept no data on there that was not somewhere else also)

Sequential read/write was around ~450ish MB a sec.

Then I switched to a single Vertex 1 (falcon) and while sequential speeds were slower, as far as an OS/APP drive it ANNIHILATED the quad raptors in a stripe as far as actual USE of the computer, which themselves would annihilate a whole pile of 80GB spindle drives in raid5, even on a fancy hardware controller card.


And FWIW, then I switched to the C300, and while it is a bit faster than the Vertex 1 in actual use, its hardly noticeable.
 
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