Quick and Possibly Dumb SSD Question

[FanIn80]

I have an early 2008 Macbook, with a 1.5 GB/s SATA interface...

SSD worth it? I know the 1.5 interface is pretty limiting, but there must be some other benefits I would gain, no?

[photon]

The huge advantage from SSDs for most types of computing isn't necessarily from the raw throughput, but from the seek times.. a normal drive is in the >10ms range, while for SSD's it's <1ms. So to load all those 100's if little files the OS needs to run, it takes hundredths of seconds rather than seconds.

And maxing out the throughput of the SATA interface won't hurt either, the drive in it probably doesn't even do that. Laptop drives are usually slower anyway.

I haven't done it yet, but I will soon, I think the impact of an SSD on a laptop is even greater than a desktop.

[Draug]

I have another question... or two... or more...

I have an OCZ Vertex 2 120gb. If I bought another one, would it make sense to Raid0 it using the onboard Gigabyte controller? 240gb would be a lot better than 120gb, but would I see any improved performance?

To install an SSD as my primary OS drive, do I need to know or do anything special in the BIOS before install Win7 64?

[photon]

You would see improved performance yes, close to double in a lot of cases. You loose the TRIM capability from the OS however as TRIM commands aren't passed through the RAID controller to the drives at this point.

This is less of an issue with the Vertex 2 and other Sandforce drives as they seem to take TRIM as a suggestion rather than a command, and they have built in garbage collection that seems to do nearly as good a job as TRIM so not a big loss I don't think.

The big issue is the issue with any RAID, is the risk of losing the array and all the data is much higher than a single drive, so make sure you have a good backup procedure.

I don't think anything special needs to be setup, just make sure you have a USB stick with the right driver for the RAID controller if Windows 7 doesn't have it built in (which it probably does). And make sure that you make the partitions through Windows 7 in the install process, it aligns them properly for max performance.

[Rathji]

Couldn't you use the Windows 7 Software RAID if TRIM support was important to you? I have never done it with a pair of SSD so it might not be as useful.

[FanIn80]

Originally Posted by photon

The huge advantage from SSDs for most types of computing isn't necessarily from the raw throughput, but from the seek times.. a normal drive is in the >10ms range, while for SSD's it's <1ms. So to load all those 100's if little files the OS needs to run, it takes hundredths of seconds rather than seconds.

And maxing out the throughput of the SATA interface won't hurt either, the drive in it probably doesn't even do that. Laptop drives are usually slower anyway.

I haven't done it yet, but I will soon, I think the impact of an SSD on a laptop is even greater than a desktop.

Yeah that's what I was thinking too, but I kept wondering if any of that would matter if I wasn't running at 3 GB/s. I didn't even think about my current drive probably not capping out anyway...

This is good news. After playing with the new MB Air with its standard SSD (man was it ever fast) last weekend, this thing has been on my mind all week.

[photon]

Originally Posted by Rathji

Couldn't you use the Windows 7 Software RAID if TRIM support was important to you? I have never done it with a pair of SSD so it might not be as useful.

Good question, not sure. Software RAID would still appear as a single drive to Windows through a software RAID driver or something like that wouldn't it?

Then it's just a question of does that driver pass on the TRIM commands, my guess would be not yet.

Really for the Sandforce based drives I wouldn't worry about it that much, after I built my machine the performance across my drive went from 220MB/s read to 180MB/s read, regardless of TRIM, and only through months of idle time to let the garbage collection do its thing has the performance come back up.. a deliberate design feature to prevent write amplification and excessive wear (which would mean early drive failure).

I read a review of the new Kingston V100+ drive and it doesn't have this "problem" of decreased performance after filling a portion of the drive since it's garbage collection is very aggressive, however the author had serious concerns about the longevity of the drive being impacted.

http://www.anandtech.com/show/4010/k...lus-100-review

Remember that NAND is written to at the page level (4KB), but erased at the block level (512 pages). Unless told otherwise, SSDs try to retain data as long as possible because to erase a block of NAND usually means erasing a bunch of valid as well as invalid data and then re-writing the valid data again to a new block. Garbage collection is the process by which a block of NAND is cleaned for future writes.

If you're too lax with your garbage collection algorithm then write speed will eventually suffer. Each write will eventually have a large penalty associated with it, driving write latency up and throughput down. Too aggressive with garbage collection and drive lifespan suffers. NAND can only be written/erased a finite number of times, aggressively cleaning NAND before it's absolutely necessary will keep write performance high at the expense of wearing out NAND quicker.

The second issue is the overly aggressive garbage collection. Sequential performance on the V+100 just doesn't change regardless of how much fragmentation you throw at the drive. The drive is quick to clean and keeps performance high as long as it has the free space to do so. This is great for delivering consistent performance, however it doesn't come for free. I am curious to see how the aggressive garbage collection impacts drive lifespan. Kingston ships the V+100 with a 3-year warranty and to Kingston's credit I haven't had any other drives die as a result of wearing out the NAND. Even if the V+100 has higher effective write amplification than the competition, your usage model will determine whether or not you bump into it.

...

SandForce continues to be the sensible choice, at least in terms of performance per dollar for a boot/application drive. I am careful to mention it as a boot/application drive because if you start storing a lot of incompressible data on the drive (e.g. movies, music, photos) then SandForce quickly loses a lot of its performance advantage. Then you're left with Crucial's RealSSD C300 which delivers more consistent performance regardless of data, at the expense of lower steady state write performance. Without TRIM, the C300 can quickly get into a not-so-great performance situation.

[photon]

On for $199 for the 120GB Vertex 2 one at NCIX lol.