4 ms·

Speaking from SSD firmware development experience, the reason is those devices are so hardware constrained (in particular SRAM and code) that the firmware team

by pkaye 7y ago

Speaking from SSD firmware development experience, the reason is those devices are so hardware constrained (in particular SRAM and code) that the firmware team spends a lot of time being clever in making it all work under huge time pressure. Couple that with SD cards being a testbed for the newest flash technology. That is why I don't use SD card for anything I care about reliability.

everybodyknows 7y ago
Any alternative suggestions for air-gapped home PC backup?
- pkaye 7y ago
  My primary concern is that those small form factor storage media might not be so reliable for backup. I'd be okay with mSATA , SATA or NVMe form factor from a reputable manufacturer. I always use something one generation behind or been out for atleast an year. Let others test the new NAND and firmware.
- pjc50 7y ago
  How do you airgap a backup?
  - everybodyknows 7y ago
    One way is to have a pool of two or three removable flash devices, with only one plugged in at a time, the others in safe places elsewhere. Automate nightly date-stamped copy to the card of just your essential data. At some interval that strikes a balance between convenience and safety, cycle the cards. You'll also need a scheme for pruning older backups to recover storage.
    - pkaye 7y ago
      In that case, understand the SSDs these days don't have great retention specs when not powered. Its one of the drawbacks of using smaller transistors and multi-level cell technology to increase capacity. When powered up they can do a background scan to scrub the data though.
      - wtallis 7y ago
        > understand the SSDs these days don't have great retention specs when not powered. The standard for consumer-grade SSDs is retention of at least a year after the drive is worn out. When the drive has been used only lightly (which is likely to be the case for a backup drive), retention will generally be several times longer. Flash memory is still not a good choice as an archival medium, but it's not like your bits are going to fade away as quickly as a rechargeable battery.
- ryacko 7y ago
  Boot from a read only device, either DVD-ROM. Copy data through a USB data diode. That is airgapped, but really expensive.
  - pnutjam 7y ago
    Get a USB sata drive caddy and mount before backing up, unmount afterwards. Swap the drive.
  - anticensor 7y ago
    Is it possible to have a unidirectional USB connection? USB is strictly master-slave.
    - ryacko 7y ago
      Yes, just like how it is possible to firewall a TCP connection. https://www.cru-inc.com/products/wiebetech/usb-datadiode/ https://www.cru-inc.com/products/wiebetech/usb-datadiode/
    - rasz 7y ago
      no, OP meant filtering write commands
  - rasz 7y ago
    "USB DataDiode" is a brand name of write blocker, all it does is block write(6,10,12) SCSI-commands https://www.os3.nl/_media/2015-2016/courses/ccf/ccf_tom_frank.pdf https://www.os3.nl/_media/2015-2016/courses/ccf/ccf_tom_fran...

by pkaye 7y ago

everybodyknows 7y ago

Any alternative suggestions for air-gapped home PC backup?

pkaye 7y ago
My primary concern is that those small form factor storage media might not be so reliable for backup. I'd be okay with mSATA , SATA or NVMe form factor from a reputable manufacturer. I always use something one generation behind or been out for atleast an year. Let others test the new NAND and firmware.
pjc50 7y ago
How do you airgap a backup?
- everybodyknows 7y ago
  One way is to have a pool of two or three removable flash devices, with only one plugged in at a time, the others in safe places elsewhere. Automate nightly date-stamped copy to the card of just your essential data. At some interval that strikes a balance between convenience and safety, cycle the cards. You'll also need a scheme for pruning older backups to recover storage.
  - pkaye 7y ago
    In that case, understand the SSDs these days don't have great retention specs when not powered. Its one of the drawbacks of using smaller transistors and multi-level cell technology to increase capacity. When powered up they can do a background scan to scrub the data though.
    - wtallis 7y ago
      > understand the SSDs these days don't have great retention specs when not powered. The standard for consumer-grade SSDs is retention of at least a year after the drive is worn out. When the drive has been used only lightly (which is likely to be the case for a backup drive), retention will generally be several times longer. Flash memory is still not a good choice as an archival medium, but it's not like your bits are going to fade away as quickly as a rechargeable battery.
ryacko 7y ago
Boot from a read only device, either DVD-ROM. Copy data through a USB data diode. That is airgapped, but really expensive.
- pnutjam 7y ago
  Get a USB sata drive caddy and mount before backing up, unmount afterwards. Swap the drive.
- anticensor 7y ago
  Is it possible to have a unidirectional USB connection? USB is strictly master-slave.
  - ryacko 7y ago
    Yes, just like how it is possible to firewall a TCP connection. https://www.cru-inc.com/products/wiebetech/usb-datadiode/ https://www.cru-inc.com/products/wiebetech/usb-datadiode/
  - rasz 7y ago
    no, OP meant filtering write commands
- rasz 7y ago
  "USB DataDiode" is a brand name of write blocker, all it does is block write(6,10,12) SCSI-commands https://www.os3.nl/_media/2015-2016/courses/ccf/ccf_tom_frank.pdf https://www.os3.nl/_media/2015-2016/courses/ccf/ccf_tom_fran...