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Questions about Solid State Drives (compared to RAM)

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April 25, 2007 1:09:29 AM

-------- the setup ----------

I work with print media daily, with resolutions of 450dpi to 1200dpi and file sizes between 500MB to 2GB. I currently have 4GB of RAM, but my scratch disk usage can range from 6GB to 18GB (so far). Currently, I use my 4-Disk RAID 0 array for scratch space, but the performance is quite slow when you compare it to how fast everything works when it is only stored in RAM.

Upgrading beyond 4GB RAM is not really an option. The motherboard only has 4 slots... and there is a 6GB RAM limit for my software anyway... so I will always need to cache data on a logical drive eventually.

Products like the Gigabyte i-RAM (4GB) or HyperOS Hyperdrive (16GB) allow you to create logical drives from RAM connected through a SATA interface. They offer great speeds, but their cost is prohibitive. (over $2000 to get a 16GB HyperDrive up and running).

So I began looking into some cheap SSD's as an alternative... Yeah, I know, SSD's aren't really cheap. But compared to regular system RAM or the above mentioned RAM-drives, you can get 4GB to 32GB drives for under $1000 now. And I think that's pretty good. My budget is about $1000.


----- the questions -------

Would a SSD offer performance comprable to RAM when used only for scratch space? What should I look for in an SSD to get the best possible performance? What are current limitations of SSDs that I should be aware of? Are there any SATA SSDs currently on the market?

My initial thoughts would be to put 4 x 4GB SSD drives in a RAID-0 array. The SSD drives would each have to offer between 30MBps to 60MBps... for combined transfer rates of over 100MBps. Can IDE SSD drives be put in a RAID?

I realize that SSD will never reach the transfer speeds of RAM (GBps), but I do not require large chunks of data all at once. The chunks would probably be between 1MB to 50MB in size...

So, would SSDs be a good choice for scratch space? Or am I fooling myself that the performance would be any better than regular hard drives in a RAID-0?
April 25, 2007 10:43:55 AM

To answer your question simply, yes SSD drives would be a decent solution in terms of their performance for a scratch disk. Now as for the noticable gain over a normal HDD, I'm not too sure how much you'll actually notice it. Also, they DO have SATA SSD drives and I think Samsung or someone makes them. I'll see if I can find it,if not you'll be stuck with IDE and yes IDE can be put in RAID, you'll just need a controller. Well, I can't find any SATA SDD drives on newegg or tiger so it looks like you'll be stuck with IDE. Your only limitation will just be your bandwidth, but that's not too bad.
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April 25, 2007 11:30:00 AM

I just read a review of a SSD (sorry can't remember where). What the review revealed is that the access time for SSD's are excellent, but sustained throughput is lower than a single HDD. So if you are dealing with lots of small files, SSD will outperform a HDD, but if you are working with large files, a HDD will demolish SSD's. Since you are interested in working with large image files, my feeling is you would be seriously disappointed with SSD. This is a problem with the NAND flash technology used in them, or more accurately the manufacturers of the NAND flash. In the article it said that the manufacturers are concentrating their efforts to increase density (storage vs. physical size) rather than performance. At some point once density has been worked out, the manufacturers would switch to improving performance.
April 25, 2007 2:51:00 PM

The op did mention raiding them. I'm thinking that if ssd's were in raid 0 you would get the best of both worlds; throughput and access time.

I would be fun to see this setup benched.
April 25, 2007 8:28:00 PM

Thanks everyone, for addressing most of my questions.

The 32GB drive from SanDisk looks very promising. It offers 62MBps transfer rates and a SATA connection, which is awesome. However, when I called them yesterday I was told it is only available as an OEM product, and they would not sell it to me individually. But DELL actually sells Parallel ATA version of the SanDisk drive individually from their website.

Unfortunately, 32GB is too large for me. I am interested in smaller drives setup in RAID-0 so that I may increase the transfer rates. The transfer rates are most important because I want the drives to act more like RAM than a regular hard drive.

...... I just noticed something about these "cheap" SSD's.. and it's their access times. Whereas more expensive SSD's offer access times similar to RAM, these consumer SSD's only offer 0.1 milisecond response times. I was honestly expected something more like 0.001 seconds. So this is it.. this is the "catch". The access times are actually no where near RAM. This is unfortunate... Also, when a press release boasts 30 seconds to boot into Windows (vs 8 or 9 seconds on a RAMdrive), I should have suspected things were not as good as they sounded.

Maybe consumer grade SSDs are not a good choice as scratch drives... perhaps I should look at getting a couple i-RAMS and just raiding those together. At least then you know you're getting the responsiveness of RAM and twice the FULL transfer rate of SATA 150...
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