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Seagate to Offer Solid State Drives in 2008
Lucas123 writes "Seagate will introduce drives based on flash memory in various storage capacities across its range of products including desktop and notebook PCs, according to Sumner Lemon at IDG News Service. The drives are expected to consume less power (longer battery life), offer faster data transfer rates and be more rugged than spinning disk, which has moving parts that can be damaged from an impact."
The rewrite issue has been rehashed a million times. It will be fine. I promise.
is projected out in the future? Normal hard drive capacity growth has certainly seemed to level off lately and perhaps is stagnating (so it seems to me). Yes, flash has grown astronomically the past few years, but is it sustainable to the point of meeting and exceeding conventional drives?
If we had the rate of growth in conventional drives that we had a few years back, we would almost certainly be looking at multi-TB drives right now.
The headache now is that most file systems are optimised for mechanical based storage media so wont this also mean we will have to look at changing to new file systems ?
There are different grades of flash chip, with varying amounts of write cycles. The problem with the kind of flash that you get in a usb keyring is not that flash is limited in the number of writes, but that cheap low-end flash is. The kind of solid state storage in a drive can take millions of write cycles, which combined with a file-system that spreads the writes evenly across he chip will give a decent lifespan.
Cost is still a major issue though. The article only has one number in it, that densities will go up to 160Gb. Do you think they'll take a cheque for that, or you do you have to spread and touch your toes in person?
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It's not all that bad. If I remember correctly, most flash memory can take 100,000-300,000.. according to wikipedia:
"while high endurance Flash storage is often marketed with endurance of 1-5 million write cycles"
I did a small research project (informational) on flash stuff recently for school, I believe solid state hard drives back in June or so were said to have about 2 million writes.
2 million writes per sector. You can always move the information around, and algorithms are being written to do that.
But, with all that, seems like hybrid drives would be the way to go right now.. after all, there's no limit on READING from solid state drives, just writing.
Not trolling, I just havent ever seen hard stats on current flash/solid state durability over time recently.
Take a 40GB hard drive, and pretend it's Flash memory. If you wrote 40GB worth of data to it every single day (with the circuitry inside a drive to spread writes out over cells evenly), then you would average 1 write per day across each cell. Flash memory can be written to a minimum of 10,000 times before dying, most is even more reliably by an order of magnitude (100,000 writes). Assuming we have crappy 10,000 write limits, we could write 40GB to the drive every day for 10,000 days, or 27 years, before failing is an issue.
Looking at the 40GB drive in one of my machines, the total writes in its uptime comes to about 800MB, which is a shade under 24 hours uptime. That's 800MB worth of writes in a day, 50 times *less* than writing 40GB to the drive every day, so a 40GB flash drive at my current usage rate could be expected to last 27 * 50, or 1350 years.
A lot longer than I have to worry about. The numbers are going to differ for some people, but the initial stats work out - few people would write to every cell every day, and even then that's decades worth of use.
I have been researching some of the more current SSD drives lately, and I know that they greatly improved the technology/algorithms behind how they write data to the physical memory. Most companies use some kind of wear-leveling techniques that evenly distribute the writes over the entire surface of the disk, maximizing the disk's life span. I have also read that the different-sized memory modules have different physical characteristics such that smaller modules are actually outlived by larger ones.
I can't give exact figures, but I've seen comparisons showing a reasonable life span (>20 years @ 100GB of writes/day) - some of the numbers are even comparable to those of spinning/mechanical hard drives. Considering how often mechanical hard drives seem to fail, it doesn't seem that there will be any major roadblocks in terms of reliability.
I know what I've written is mostly qualitative (apologies on that), but I know the research into how to mitigate the problem of life span has truly advanced in the last few years as interest in SSD has increased. Jim Gray of Microsoft Research fame, predicted that SSD would replace mechanical drives not far off from now. Check out his paper "Flash Disk Opportunity for Server-Applications" for more on that.
SixD
All modern flash drives use write levelling to ensure writes
are evenly spread across the device.
This article
takes those numbers and using a hypothetical "write logger" app that
continually writes, estimates an average life of 51 years.
MTron specs for their SSDs estimate:
So lets lay this one to rest. SSDs are worth it.
I did some poking around the net for information on NAND write cycles. They've already been quoted in the comments here (100,000 to 2,000,000) so I'm just going to post this neat white paper I found on Zeus drives that explains the endurance they get from their SSD Drive. http://www.baydel.com/images/gallery/NAND%20flash% 20resilience.pdf
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The drive controller will do wear leveling, so it will not rewrite the same bits over and over again, even if the OS thinks it does. This has also been rehashed a million times.
Relax, they still sell mechanical hard drives.
For that matter, how come we never saw magnetic drives with builtin RAM caches in the GB scale, occasionally written (in parallel) back to the magnetic disc for reliability?
Possibly because you weren't looking. For all I know, they still exist, but the vendor we got one from went out of business a few years ago. They sold full-length PCI cards packed with 8GB of SDRAM -- and they had larger models -- that presented a SCSI interface to the system and, with the appropriate driver, could mirror to a magnetic drive. The cost was stratospheric, and our storage needs soon outgrew the available space. We also found that not as much of our processing was I/O-bound as we thought. Other than that, it worked great. Given enough money and a motherboard with a sufficiently large number of PCI slots, it might be the ideal solution for certain niche applications, but the cost and size constraints otherwise make them a poor substitute for magnetic drives in most cases.
That said, it was pretty cool to be able to reformat the "drive" in a few seconds.
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Flash drives simply don't write the same first bits over and over again. Their firmware is programmed to 'intelligently' spread written data across the entire storage area as fairly as possible.
Between this, massive storage capacity (think: 'dilution') and what will surely be engineering improvements, flash drives should prove to be very reliable.
I for one, welcome out solid state overlords.
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