Quote:
Originally Posted by cc_in_oh
I think I paid around $70 for my 240GB SSD a year or 2 ago. I was pricing new PC's last month and wondering why anyone would bother with Optane memory when SSD prices are where they are these days. They must have made enormous strides in reliability recently If they can hold up to the kind of rewrite activity you get on a large database sever - it hasn't been that long since they were recommended only for relatively static storage...
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Back when I began looking at them, the techs I hang out with (sysadmins, network engineers and the like) tended to say "You buy the high priced spread and get Intel. It costs more but it's less likely to fail."
These days, things
are a lot more reliable. Online posts of torture tests had even budget line SSDs requiring
petabytes of writes before they failed.
There are about five companies that make the actual NAND flash used in SSDs. Everyone else sources from them and puts their name on the label.
The flash media itself is quite reliable these days. An area of advance has been firmware. The firmware on SSDs tries to distribute writes evenly across the entire drive. (Because any part of the SSD can be accessed in the same amount of time, you aren't concerned with fragmentation or just where something is stored, only that you can reach it and read or write it.)
SSDs are organized as cells, and I believe the sort of flash used in current consumer SSDs has a limit of about 10,000 writes before a cell reaches the limit and becomes unusable. They are over provisioned, with spare cells to substitute if any reach the limit. The firmware tries to track that and migrate data to a spare cell and mark the one about to fail as bad.
Degradation will be graceful, and show as decreasing storage as cells reach the limit and get marked unusable and the drive has run out of spares.
How long do you think it will take any individual cell in an SSD to get written to
10,000 times? For consumer SSDs, which are read from far more than written to, you are likely to replace the machine the SSD is in long before you
notice drive wear.
It won't be a lot worse for a database server, as read only look ups will happen a lot more than updates that require writes. (And a database server will be backed up regularly in any case.)
I got a 240GB Crucial SSD for my previous desktop, and it cost about $100. The price has dropped since. When the prior desktop had a power supply failure, and the Small Form Factor design meant I couldn't just replace the PS, I got a new desktop and repurposed the Crucial SSD. It's been working fine.
I've looked at Optane, and it's neat, but I don't have use cases that justify what it costs.
What does interest me is that the distinctions between RAM and flash storage are fading. Flash is getting fast enough that a machine down the road might have
only flash that will be both nonvolatile storage
and system memory that is used like RAM.
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Dennis