Even if it isn't high performance for an NVMe SSD, I still find the size of that form factor amazing, however, I am old enough to remember 8 inch floppys.
Gotta be careful with data access on those: if you were bored (or malicious), you could read/write data alternately on the inside and outside tracks of the platters, causing the (comparatively) massive R/W head arm to swing rapidly back and forth, and the whole unit could start to walk away on you.
The thing that would worry me, and I wonder if anyone thought this through....
If it uses system RAM for hosting the mapping info for the LBA -> page map... what happens if the system:
1) isn't using ECC and there's a bit error. 2) has a typical misbehaving program which corrupts the LBA mapping. 3) has a deliberately malicious program muck with the LBA mapping. 4) loses power during a write.
Any one of those three issues could create big problems with the drives and the stability of the system.
The host memory buffer memory is supposed to be set aside by the OS for the exclusive use of the SSD, so cases 2 and 3 would require an OS/driver bug, not just a misbehaving application. (Or a successful DRAM rowhammer attack.)
Any SSD using HMB must be prepared to immediately relinquish that memory back to the host system, so in practice HMB is used as a write-through cache, not a write-back cache. That means there's nothing worse about a sudden power loss when you're using HMB.
Lack of ECC is theoretically a problem, but given the small amount of DRAM used for HMB, the expected error rate is really small and not a concern for most of the applications that would use this kind of SSD.
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BillBear - Thursday, August 3, 2017 - link
Even if it isn't high performance for an NVMe SSD, I still find the size of that form factor amazing, however, I am old enough to remember 8 inch floppys.abrowne1993 - Thursday, August 3, 2017 - link
If the floppy is 8 inches I'd hate to see the hard disk.Stan11003 - Thursday, August 3, 2017 - link
https://www-03.ibm.com/ibm/history/exhibits/storag...They were the size of a mini fridge and cost up to $87K
edzieba - Friday, August 4, 2017 - link
Gotta be careful with data access on those: if you were bored (or malicious), you could read/write data alternately on the inside and outside tracks of the platters, causing the (comparatively) massive R/W head arm to swing rapidly back and forth, and the whole unit could start to walk away on you.bill.rookard - Thursday, August 3, 2017 - link
The thing that would worry me, and I wonder if anyone thought this through....If it uses system RAM for hosting the mapping info for the LBA -> page map... what happens if the system:
1) isn't using ECC and there's a bit error.
2) has a typical misbehaving program which corrupts the LBA mapping.
3) has a deliberately malicious program muck with the LBA mapping.
4) loses power during a write.
Any one of those three issues could create big problems with the drives and the stability of the system.
Billy Tallis - Thursday, August 3, 2017 - link
The host memory buffer memory is supposed to be set aside by the OS for the exclusive use of the SSD, so cases 2 and 3 would require an OS/driver bug, not just a misbehaving application. (Or a successful DRAM rowhammer attack.)Any SSD using HMB must be prepared to immediately relinquish that memory back to the host system, so in practice HMB is used as a write-through cache, not a write-back cache. That means there's nothing worse about a sudden power loss when you're using HMB.
Lack of ECC is theoretically a problem, but given the small amount of DRAM used for HMB, the expected error rate is really small and not a concern for most of the applications that would use this kind of SSD.