Does this remind anyone of the "Hard Card", from Plus Development? They were 3.5" hard drives mounted on an ISA card way back in the day. It's funny how technology is sometimes cyclical.
Ugh, I really wish the marketing people would pick different name for this evolution of SSD drives then NVMe. At least the NVM part stating: Non-Volatile Memory.
The current iteration of what we call NVM is just SSD on PCIe busses so they are not bound by the speed of SATA/SAS controllers.
Maybe it's just me but when I think NVM I think of Non-Volatile Memory something like RAM that doesn't go blank when you hit the power button. And like RAM can be mapped into (kernel or user) address space. And access to them go through processor caches (L2 or L3) strait into NVM.
The current SSD+ drives very much behave like the block devices of the old, just with a different host interface. Most importantly they can't be directly memory mapped without going through the page cache. That still leaves a lot of performance on the table (double copy, requiring RAM for page cache versus working set).
This grossly undersells and undersimplifies the value of NVMe, its wire protocol is fundamentally simplified and it features an unlimited number of queues of unlimited depth with individual interrupt (read: CPU core) routing per queue. SATA is nothing like that. Also, the term NVM has been in use since at least the 80s to refer to probably 50 different technologies by now.
Most importantly they can't be directly memory mapped without going through the page cache.
It's been ages since I last did anything with PCI MMIO, but it was definitely possible to map PCI devices' own memory into a process's address space using /dev/mem, and into kernel space as well. Is there no longer an equivalent concept for PCIe? Or was MMIO always attached to real RAM?
idle power consumption: 4 Watts - way too much for my taste... I can understand it needing 22 Watts during high speed writes but why this much during staying idle ?
for comparison I checked my external 2TB WD Passport 0820 harddisk - it uses 2.11 Watts when streaming HD video...
I agree, that's some high idle power consumption. If I had to hazard a guess, it's the controller aggressively maintaining the charge of the flash cells [1]. Samsung released a fix, not too long ago, for a bug with flash cells losing charge for their 840 and 840 Evo SSD line [2], so I imagine it's a delicate process to get right. Are the other NAND controllers less aggressive and/or more efficient with this process? I don't know. I assume it's the same flash cells as the SATA drives but with a PCIe-oriented controller, so I hardly expect them to lose charge any faster than the SATA counterparts.
That's an understatement. It's unbelievable to me how quickly we have moved from <100MB/sec drives being the norm to (relatively) inexpensive 1000+MB/sec drives with incredibly fast seek times.
Now if only the laptop manufacturers would include SSDs in more mainstream models. It's depressing walking into the average computer retailer and seeing practically every shelf stuffed with slow HDs and salesmen trying to pitch the huge importance of minor differences in processor speed.
[+] [-] nitrogen|11 years ago|reply
As a comparison, the 1TB Samsung 850 Evo uses 5.7W maximum for writing at 520MB/s (91MB per second per watt).
[+] [-] justincormack|11 years ago|reply
[+] [-] tlb|11 years ago|reply
[+] [-] frozenport|11 years ago|reply
[+] [-] derekp7|11 years ago|reply
[+] [-] bhauer|11 years ago|reply
Both those numbers are but a quaint memory.
[+] [-] yuhong|11 years ago|reply
[+] [-] mtanski|11 years ago|reply
The current iteration of what we call NVM is just SSD on PCIe busses so they are not bound by the speed of SATA/SAS controllers.
Maybe it's just me but when I think NVM I think of Non-Volatile Memory something like RAM that doesn't go blank when you hit the power button. And like RAM can be mapped into (kernel or user) address space. And access to them go through processor caches (L2 or L3) strait into NVM.
The current SSD+ drives very much behave like the block devices of the old, just with a different host interface. Most importantly they can't be directly memory mapped without going through the page cache. That still leaves a lot of performance on the table (double copy, requiring RAM for page cache versus working set).
[+] [-] _wmd|11 years ago|reply
It's not a marketing trick
[+] [-] nitrogen|11 years ago|reply
It's been ages since I last did anything with PCI MMIO, but it was definitely possible to map PCI devices' own memory into a process's address space using /dev/mem, and into kernel space as well. Is there no longer an equivalent concept for PCIe? Or was MMIO always attached to real RAM?
[+] [-] knweiss|11 years ago|reply
This is the "Persistent Memory" device class. See e.g. this article for a nice summary of the status quo: https://lwn.net/Articles/636096/
[+] [-] imaginenore|11 years ago|reply
1TB SSD is now around $350-360 on Amazon.
[+] [-] wmf|11 years ago|reply
[+] [-] vladtaltos|11 years ago|reply
for comparison I checked my external 2TB WD Passport 0820 harddisk - it uses 2.11 Watts when streaming HD video...
[+] [-] kileywm|11 years ago|reply
[1] http://www.purestorage.com/resources/introduction-to-flash-m...
[2] http://www.anandtech.com/show/8617/samsung-releases-firmware...
[+] [-] rasz_pl|11 years ago|reply
Not to mention you can cram SM951 into a laptop.
[+] [-] tracker1|11 years ago|reply
[+] [-] _ea1k|11 years ago|reply
Now if only the laptop manufacturers would include SSDs in more mainstream models. It's depressing walking into the average computer retailer and seeing practically every shelf stuffed with slow HDs and salesmen trying to pitch the huge importance of minor differences in processor speed.