231–240 of 258 posts
I worked on SSD firmware for quite a long time and here is my perspective. Early flash used to fairly reliable with almost minimal error correction. However with increasing density, smaller processes and multi level cells, it has gone progressively less reliable and slower. Here are some of the things that we need to worry about: https://www.flashmemorysummit.com/English/Collaterals/Procee... To compensate for all th…
With the older drives you sometimes would have a drive die, replace it, restore your backup only to find that in the process of dying the drive was actually corrupting some of the data which went into the backups, now you've got to hunt down the last uncorrupted versions of the data in the backup…
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You still get paid a lot more working at google working on generic backend protobuf shuffling than you will working on SSD firmware at a hardware company or intel's C++ compiler.
Compiler hacking, OTOH is a lot of fun and actually quite rewarding when other devs use your product.
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The electrons aren't shot through the insulation. They end up in the floating gate by quantum tunneling. The insulation by its name is non-conductive, and must be so that the electrons stay put. The degradation happens through general thermal wear.
The exact wear mechanism doesn't really matter (you must be referring to "hot carrier injection") --- the point is that to record data, electrons are being forced through a material which gradually wears it out.
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"It feels like the author's main complaint is the frustration of not understanding SSD hardware as well." What is so frustrating about SSDs is how very poorly they compare to previous incarnations of solid state storage. Using Disk-On-Chip and/or IDE-pin-compatible CF cards, I had many, many devices in the field that lasted, mounted read-only, for decades An entire sect of the computing industry came to rely on these…
I've heard very similar advice for non-SSD mirrors too. Use different manufacturers or, at the very least, use different batches of disks from the same manufacturer.
Also, though, because most serious RAIDs contain more drives than you can find manufacturers of hard drives.
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> I've seen lots of writeups of how wear-leveling works, etc., but never a good physical explanation of what is actually wearing out over time. SSDs are flash are basically EEPROMs. In an EEPROM one bit is stored in a dual-gate MOSFET. One Gate is a normal gate, the other is floating, i.e. it just is a small conductive island. The information is stored by (quite literally) shooting electrons through the insulation of…
The electrons aren't shot through the insulation. They end up in the floating gate by quantum tunneling. The insulation by its name is non-conductive, and must be so that the electrons stay put. The degradation happens through general thermal wear.
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Physical devices don't have SLAs, because they aren't services. SSDs have the physical equivalent of an SLA, a warranty. I haven't seen stats, but in my experience the odds of an SSD dying within the warranty period is very very low. If you want your storage to have an SLA, storage service providers exist, and will be happy to give you an SLA if you're willing to pay. But it isn't cheap.
> Physical devices don't have SLAs Yes, I know that. That's why I said "essentially". > SSDs have the physical equivalent of an SLA, a warranty. There are two orthogonal issues. The first is what happens when a device fails. A warranty addresses that. The second is how does it fail. Does it fail all at once with no warning, no way to perform post-mortem diagnostics, and no way to recover the data? Or does it fail wit…
This is not a technological problem, it's a cultural one. These problems are easily fixed ("easily" by the standards of technical problems that regularly get fixed in other regimes). The reason they don't get fixed is that the customer reaction to failures like this is to rant at the mysterious storage gods that are making their lives miserable. Needless to say, there are no mysterious storage gods. These are artifac…
Physical devices don't have SLAs, because they aren't services. SSDs have the physical equivalent of an SLA, a warranty. I haven't seen stats, but in my experience the odds of an SSD dying within the warranty period is very very low. If you want your storage to have an SLA, storage service providers exist, and will be happy to give you an SLA if you're willing to pay. But it isn't cheap.
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You still get paid a lot more working at google working on generic backend protobuf shuffling than you will working on SSD firmware at a hardware company or intel's C++ compiler.
For those doubting you, the going rate for embedded engineers out here in the Denver area where a lot of these SSD controllers are designed is ~$90k. Embedded engineers get peanuts for some reason.
The solution for this would be to open source such projects so engineers from many smaller companies can collaborate. These companies needs to understand that they will not be able to attract top talent and collaboration instead of competition is the way forward.