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Top Solid State Disks and TB Drives Reviewed
Lucas123 writes "Computerworld has reviewed six of the latest hard disk drives, including 32GB and 64GB solid state disks, a low-energy consumption 'green' drive and several terabyte-size drives. With the exception of capacity, the solid state disk drives appear to beat spinning disk in every category, from CPU utilization, energy consumption and read/writes. The Samsung SSD drive was the most impressive, with a read speed of 100MB/sec and write speed of 80 MB/sec, compared to an average 59MB/sec and 60MB/sec read/write speed for a traditional hard drive."
The no-moving-parts characteristic is, in part, what protects your data longer, since accidentally bumping your laptop won't scramble your stored files. Samsung says the drive can withstand an operating shock of 1,500Gs at .5 miliseconds (versus 300Gs at 2 miliseconds for a traditional hard drive). The drive is heartier in one other important way: Mean time between failure is rated at over 2 million hours, versus under 500,000 hours for the company's other drives.
I'm really interested in the SSD drives as high performance replacements (particularly for holding OS images where boot times should be nicely reduced), but I've got to wonder how the mean time to failure of one of these compares to a traditional magnetic disk. I know they use write leveling, but that just means everything will have a tendency to fail around the some time later, rather than a spot or two now and then. Anyone have any actual reports on these? I can usually make it 2 or 3 years before I start to see errors crop up on magnetic disks (sometimes more or less depending on how much thrashing the disk is subjected to). Might it be cheaper to simply buy a decent sized CF or SD card and an ide/sata adapter rather then paying for an actual disk, or is there some inherit advantage to one of these you'd be missing out on?
Curiosity was framed, Ignorance killed the cat.
Write Cycles: Even at the lowest estimate, 100,000 write cycles to failure
Meaning on a 32GB Drive, before you start seeing failures, you would have to (thanks to wear-leveling) write 32*100,000 GB, or 3.2Petabytes
at 60MB/sec write speed of the Samsung drives, you would need to write (and never, ever read) for 3,200,000,000/60, or ~53Million seconds straight.
53Million divided by 86,400 means you would need to be writing (and never ever reading) for ~617 Days straight (That's roughly 20 months of just writing, no reading, no downtime, etc...
So... the sky is not falling, these drives are slated to last longer than I've ever gotten a traditional drive to last in my laptop(s)
Almost forgot to mention, standard NAND of late has been more in the 500k-1M write cycle between failures range. 100k was earlier technology, so multiply numbers accordingly.
Will this ever die? The write cycle counts in modern flash is in the millions now. Doing the math you very easily get 20+ years before write cycle wear is a concern: http://www.storagesearch.com/ssdmyths-endurance.html
How many heavily used spinning drives do you know that last even 10+ years?
If you want, buy an HDD and a Flash-Drive of the same cost, hook them up to a program that runs each at equal data-transfer rates, and see how much data you can read and write to each before they fail. Report back to us in the six months it'll take you.
Oh, and you need to do the trial over a wide sample, so get, oh, at least ten of each.
Actually the endurance on NAND has been going lower over the years as they switched to smaller cell geometry, larger capacity and MLC technology. Some are as low as 5000 cycle endurance. These MLC(multi-level cell) NAND tend also to be much slower than SLC(single-level cell) NAND. Most SLC NAND have around 50K or 100K endurance.
I am still waiting for a reasonably priced low-end drive. An 8GB usb drive can be found for about $50. Packing 4 of them and replacing the usb circuitry with SATA would make for a 32MB for $200. Granted, it may not be the fastest drive around, but sometimes speed is not the most important factor. A 32MB would be enough for installing any current OS and still have some room for personal files to carry along on a trip. So, I think the current trend of providing high-end drives only is just an attempt to milk users to the maximum without much concern for what we actually need.
And this is why we're moving away from NAND, so get that damned term out of your head already! OUM/OVM is coming, uses a nearly identical manufacturing process (It's the same thing found in RW optical media, except you use electricity instead of a laser to change it's state) as CMOS does, and it has FAR more read/write cycles than anything NAND could have ever hoped to achieve, in the range of 10^8 as opposed to NAND 10^5-10^6
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
Some friends of mine at another company that were using them in a I/O laden system that wanted to replace laptop drives to make the machinews lower power and more reliable can blow out a flash drive in about 4 weeks.
Kirby
No need to compare with 15k rpm drives; flash disks lose spectacularly to low rpm laptop drives for random write performance. For obvious reasons though, no one ever tests random write performance. Manufacturers also rarely report random write IOPS.
Flash is great, if your disk is basically read-only.
Yes I have. However, I've never had one magically get smaller on me in such a way that fsck decides that your done fixing the filesystem. With SSD, YES, I've had exactly that happen to me.
In my life, I've lost a total of about 42Kb be completely unrecoverable with spinning media (yes, I mean that number literally). I use RAID extensively, I was the DBA/SA/Developer at a place that had ~10TB of disk online for 5 years. In all that time, 42KB is all I lost. Oh, that was in the off-line, tertiary backup of the production database (it was one of 5 copies that could be used as a starting point for recovery, we also had the redo logs for 5 days, each DB was a snapshot from one of the previous 5 days). It was stored on bleeding edge IDE drives put in a RAID 5 array. We used it as a cheap staging area before pushing the data over Firewire/USB to a removable drive that an officer of the company took home as part of the disaster recovery system (it had only the most recent DB and redo logs). The guy didn't RMA the hot spare, and we had two drives fail in about 3 days while the hot spare was waiting for the RMA paper work to fill out. In that one particular case, using ddrescue, I recovered all of the data off of the RAID5 array but 42KB (even though it was an ext3 filesystem on LVM, on a RAID5 array, which made the recovery even more complex). Every other bit and byte of data in my life from spinning media that I cared about, I've recovered (I've had a number of drives die with data I didn't care about, but I could have recovered from if need be). Trust me, I know about reliability, backups, and how to manage media to ensure that failure doesn't happen. I know about failure modes of drives. I've hot swapped my fair share of drives, and done the RMA paperwork. I've been in charge of drives that losing any one of the ~200 drives would have cost 10 times as much as I made in a year if I couldn't reproduce the data on it within hours.
If it had been worth $10K, I'd have sent off the drive to get that 42KB of data recovered. But it wasn't. It's well understood how the failure mode of spinning media. People know exactly how to do things like erase drives securely. People know who to call that has a clean room that can remove the magentic media to and put it under a microscope to get the data recovered. SSD isn't nearly as mature in that sense.
All of that is really to say: Yes, I know something about disks and drives. My point is to say that SSD's aren't magic pixie dust in terms of reliablabilty. I've had exactly what he's saying I shouldn't worry about happen to me on a regular basis. Enough, that our engineering department has developed specific procedures to deal with them in the field. We've changed our release procedures to accout for them. If your going to use an SSD or flash drive, go kick the crap out of it. Don't believe on faith anything you read on Slashdot (including this post, which is anecdotal). We order lots of 5,000 flash disk, and you can bet that at least 100 of them has serious flaws within being fielded. The ones the developers and testing uses regularly develop problems in terms of months, not years. The manufacturer tells us essentially, it's not worth it to find those, so deal with it.
The whole point of replacing the laptop drive was to make the silly thing more reliable. But making it uber-reliable for 4 weeks until the write leveling crapped out wasn't the idea.
Kirby
When I was young and stupid about drives and media, I lost a 1.2GB WD drive and lost everything on it. I couldn't spell "mkfs" or "fsck" and had no idea how to recover the drive at the time (I also didn't have the money to have a second drive to recover too, and no credit card so I could hold onto the first while having the second during the RMA). I was just young and ignorant. I lost a 1-2GB laptop drive that I literally just rode into the ground, I could have copied everything off and moved along. I knew the drive was going bad, but it was just a knock around system that I didn't care about. In the end, had I been thinking, I'd have saved the e-mail on it. I lost the first ~5-6 years of e-mail I had, but who wants e-mail from when they were 18-24? That was probably a couple of hundred MB that I might regret, but of nothing more then sentimental value. I'd never read it, and only be amused that I could prove I'm getting the same chain letters 15 years later.
I believe I had 4-5 drives I lost due to a virus or pilot error, but not a mechanical/media problem.
I've RMA'ed probably 100-200 drives due to some type of failure. I've had lots of of drives fail that were in a RAID array, that the mirror saved me. I've had lots of drives fail that were stand alone that had a section of bad sectors. All of that I recovered every byte of data from. Normally a drive that is going bad, you can still recover from for a very limited amount of time. Normally you have plenty of lead time, especially with SMART drive monitoring that your drive is going south. As long as you pay attention, spinning media isn't that hard to keep in good shape.
As a professional IT person, 42KB is it. On machines where production work is done for money at a company. 42KB is it, and in that case I was bound and determined to recover absolutely everything, and I invested a week into that project. I gave up on the 42KB once I proved that it was in a backup for the database that was at that point 15 days old (and thus of no use). Had it been necessary or cost effective, I'd have spent the $1-3K to get that drive images recovered by a professional data recovery shop. I think I've lost a drive or two on my personal machines at work, but the drive was fine, the laptop SATA controller was overheating. Using FSCK, I recovered the entire FS once the RAID controller was replaced. I think I had to re-rip some music from CD, because I failed to back it up prior to sending the laptop in for repair. I re-imaged the drive just to be safe in case the RAID controller had corrupted something important on the OS drive, which was the only reason I actually lost the music.
Again, it's the fact that the flash drives we have decided the drives are smaller at the interface level. Using fsck just scragged the system pretty much start to finish. I don't have a clue where the missing blocks are from. I have no idea what happened, upon reboot it decided that the block devices was smaller. Filesystem recover tools haven't had a chance to mature to understand those types of failures. Flash makers haven't yet decided that access to diagnostics and re-mapping logs might be of value to data recovery tools (at least none that I'm aware of). Access to the raw data (in case they are holding blocks in reserve). All of these things are reasons to be concerned about write leveling.
Kirby