Linked by Thom Holwerda on Thu 27th Sep 2012 19:36 UTC
Apple I bought a brand new iMac on Tuesday. I'm pretty sure this will come as a surprise to some, so I figured I might as well offer some background information about this choice - maybe it'll help other people who are also pondering what to buy as their next computer.
Thread beginning with comment 536725
To view parent comment, click here.
To read all comments associated with this story, please click here.
RE: Something important missing
by Alfman on Thu 27th Sep 2012 21:10 UTC in reply to "Something important missing"
Alfman
Member since:
2011-01-28

bowkota,

Even though SSD's are becoming affordable, I'm not keen on their falling reliability levels. First there was SLC - 1 bit per cell, then MLC with 2 bits per cell (4 voltage levels). Now we're seeing 3 bits per cell (8 distinguishable voltage levels). This produces higher capacity drives for very low manufacturing costs.

Each generation is moving towards ever smaller manufacturing processes: from 100nm in 2007 to 20nm today. This means more cells per area, but also that fewer electrons are available to represent a bit state, and increasing the likelihood of getting stuck electrons.

Combine both of these trends and it spells disaster for reliability. I experienced my own data loss, which is why I've been researching these things.

I looked up the specs for NAND chips used in my device, and they officially only spec 3K program/erase cycles before loosing data integrity!!! This is much lower than the million write cycles we had using 100nm SLC NAND.

3,000 P/E cycles (with 24 bit/ 1,024byte ECC)

http://www.jm-chip.com/en/down/H27UBG8T2A.pdf
(link is down)

http://forums.anandtech.com/showthread.php?t=2144579
(they talk about it here)

Flash devices use smart controllers to distribute the writes across all cells of the NAND chip to alleviate the effects of any individual sector updates on the logical media. This is fine assuming most sectors rarely change. However if you have a data load that routinely rewrites significant portions of the flash disk - then the average cell lifespan will be consumed fairly quickly. Due to the write-distribution algorithm there is a good chance that all NAND pages will reach EOL at approximately the same time, so once data errors are discovered, there are probably more errors that haven't even been discovered yet.

Not saying it's for nobody, but do your research... failure is common. By all means keep backups! ( Ideally not on flash drives ;) )

I've been trying my own hand at performing data recovery off failing flash media, so if anyone does get unrecoverable flash media, I might be able to offer my services ;)

Reply Parent Score: 3

Morgan Member since:
2005-06-29

Regarding SSD reliability: I've always been of the mind that you should run your OS and installed programs on the SSD for the speed gains and keep your data on a traditional HDD to avoid data loss. On GNU/Linux and BSD this is easy; during installation just put your /home on the HDD and you're good to go. On Windows you can point your User folder at a different volume with a few extra steps after installation.

Reply Parent Score: 4

WereCatf Member since:
2006-02-15

Regarding SSD reliability: I've always been of the mind that you should run your OS and installed programs on the SSD for the speed gains and keep your data on a traditional HDD to avoid data loss. On GNU/Linux and BSD this is easy; during installation just put your /home on the HDD and you're good to go. On Windows you can point your User folder at a different volume with a few extra steps after installation.


That's what I am planning to do once my SSD arrives: I'll move my Downloads - folder and most of the contents inside Application Data to a regular disk and link them to their appropriate place via NTFS junction points, but I'll keep Firefox's cache on the SSD because there's a gazillion files there and they're all very small ones -- a situation where an SSD excels and a regular HDD doesn't.

Would be nice if Windows offered some tools for trimming off the fat, though; at the moment my Windows - directory takes 23 gigabytes of storage, and that's not including my home directory, Program Files or anything like that.

Reply Parent Score: 2

UltraZelda64 Member since:
2006-12-05

I agree, this is the way to go if you happen to have an SSD. SSD for the system, hard drive for data. But I have to admit that I don't trust SSDs for the long term--even when used as a system drive. For example, if you regularly do a fresh install of your OS while keeping your /home directory intact, and you use a distro that has a release cycle of under a year, how many OS installs will you be able to do before bits start to go bad? Never mind the typical package updates throughout the lifespan of a distro; there are usually lots of those.

The fact that these things have to even be considered makes hard drives a more attractive choice in my opinion. Also, if you're a distro hopper you may run into problems sooner. What about swap space... should you put your swap partition on a hard drive, and then suffer the slowdown of using a hard drive anyway (eliminating one of SSD's biggest advantages) as soon you start running out of RAM--all because the SSD cannot be trusted for frequent rewrites?

Instead of getting one expensive drive that is just big enough to hold one OS and does not have proven reliability, I honestly think you'd be better off just getting a larger hard drive and partitioning it. Or even get a smaller "system" hard drive, and a bigger one for data. Sure, hard drives are also not known for their low failure rate, but at least they've been tried, tested and proven over the decades. It's a technology you can at least somewhat trust.

Modern computers and hard drives are so damn fast anyway, I honestly can't imagine an SSD being that big of an improvement over a good quality hard drive, performance-wise. Where SSD can truly beat the shit out of hard drives, though, is in laptops and similar portable devices; no moving parts means no physical damage, crashing, and data loss by accidentally dropping or bumping the computer. IMO, that is where SSDs truly shine. Then again, even in laptops I often hear about the battery or a corrupt/infected Windows installs far more often than a crashed hard drive.

Reply Parent Score: 2

lfeagan Member since:
2006-04-01

The firmware can also greatly help or hinder the reliability of a particular flash chip.

You should always be prepared by keeping regularly backups with one of the many free or commercial backup programs--regardless of using an SSD or a spinny disk.

Reply Parent Score: 1

lucas_maximus Member since:
2009-08-18

I think it is fairly evident that you should have a decent backup plan SSD or not.

This is not new.

Reply Parent Score: 3

iswrong Member since:
2012-07-15

Yup. I have an SSD in my MacBook Pro. The difference is like day and night. My work machine still uses a hard disk and it is annoyingly slow.

I use onsite backup (Time Machine) and offsite (backblaze), so when my SSD crashes, I'd be up and running again in no-time. Not that I am too worried about it, because the average SSD lifetime is a lot longer than I use a particular machine.

Reply Parent Score: 2

Alfman Member since:
2011-01-28

lucas_maximus,

"I think it is fairly evident that you should have a decent backup plan SSD or not.

This is not new."

Of course you should have backups. But what is new compared to HDD is that NAND flash itself has a very limited number of writes before dying, even if none of the components have broken down. A hard drive can obviously break down, but as far as I know it's media can take virtually unlimited number of writes without worrying about significant data integrity losses.

Reply Parent Score: 2

bassbeast Member since:
2007-11-11

Good luck on recovery as I've tried my hand at it too and with SSDs it seems like the controller goes bad more times than not so you are just boned. this is one of the reasons i always push my "backup backup backup" mantra upon customers, especially my gamer early adopters, as its just too easy to get bit by new tech failing.

But this is why I say there are places where SSDs make sense and places where it doesn't. If its a mobile and you have a USB drive to backup important data? Makes sense as no moving parts and you can easily slap the drive you pulled from the unit to go SSD into an external case and use it for a backup. Gamers where its just the OS and a few games? Again makes sense, they can have a disc image and if it dies just use a HDD until your replacement arrives. Businesses or anything that is mission critical? Does NOT make sense, the risk of failure and the cost of downtime makes it not worth the extra speed.

So I'd say SSDs are like any other tool in that you have to know where its a good fit and where its not. I'll personally switch my HDD in my netbook for an SSD after the first of the year, the extra battery life and faster boot times will make it worth the hassle and risk. On my desktop where I only put the system to sleep? Not gonna bother because with 8Gb of RAM for Superfetch even with my OS drive being a 5400RPM EcoDrive it just wouldn't be worth the increased risk.

Reply Parent Score: 2

Alfman Member since:
2011-01-28

bassbeast,

"Good luck on recovery as I've tried my hand at it too and with SSDs it seems like the controller goes bad more times than not so you are just boned."

Well, I actually desolder the NAND chips and work on data reconstruction from there so I'm not limited to recovery through a bad controller.


"But this is why I say there are places where SSDs make sense and places where it doesn't."

That's the bottom line. I'm hoping reliability problems are solved. Maybe one of these alternatives will replace NAND all together:

http://arstechnica.com/information-technology/2012/07/the-future-of...

Reply Parent Score: 2