-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Thursday, 2017-12-14 at 10:34 +0200, Dave Plater wrote:
On 13/12/2017 15:55, Greg Freemyer wrote:
Long ago I knew more about the chips. We used to refer to DRAM for dynamic ram. The bits in the DRAM chips would disappear in a few seconds (or less) of the data wasn't refreshed by a strobe.
It is clear that NVMe SSDs don't use DRAM chips, but could one call the chips they use RAM, I don't know. I'm sure they have the internal erase block (EB) feature/architecture of SATA interfaced SSDs.
The EB architecture means the data once written is stable until electricity is used to erase a block of memory for re-use. There is a controller that lives on the SSD that manages the EB allocation and sector mapping from a logical sector to a physical EB and internal EB offset. To me this is nothing at all like what I think of when I see the term RAMDISK.
Greg It's official, the nand flash chips used by ssds and nvme disks are block readable and writable only, so they can't be classed as random access memory which every location from address 0 and up is accessable in a random fashion.
Ah, this is what I thought. So the motherboard can address directly a block, not a word, on these devices. Once the block is addressed, I does something to transfer to RAM, either inside the disk or on the mother board. I suspect first to internal RAM, then this RAM is directly accessible from the motherboard, maybe via DMA. Unless there is a way to do a DMA transfer directly from the nand flash, emulating direct access to a position even if it is sequential. Some trick I can just imagine but not describe. - -- Cheers, Carlos E. R. (from openSUSE 42.2 x86_64 "Malachite" at Telcontar) -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iEYEARECAAYFAloyd/UACgkQtTMYHG2NR9UoswCfbsovyNIPkfwvrm2qUOPAqTY1 wj0Ani7zG9Vp3KgYufXBn5N6i4M39nsU =tknE -----END PGP SIGNATURE----- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org