4 ms·

Its only now that HDDs are close enough to the density of tape (4Tbs) however lto6 is half the price, and designed for the job. HDDs are not designed for long

Its only now that HDDs are close enough to the density of tape (4Tbs) however lto6 is half the price, and designed for the job. HDDs are not designed for long term archive. They simply fail hard when being moved or switched off for a long time.

skrause 13y ago
> HDDs are not designed for long term archive. They simply fail hard when being moved or switched off for a long time. A single disk certainly is bad for long term archive. But when you have thousands of disks and use multiple copies for all data with some fancy error correction you can still get extremely high reliability, you just need to calculate in the expected failure rate.
- KaiserPro 13y ago
  High failure == high cost.
acdha 13y ago
> HDDs are not designed for long term archive. They simply fail hard when being moved or switched off for a long time. This is also surprisingly easy to do with tape - simply leaving an LTO tape on its side can push failure rates to significant levels within a year. If you care about data there's no substitute for multiple copies which are regularly verified. The idea that you can leave something on the shelf and expect to reliably read it is a dangerous myth. If you care about archival, build a system with the staffing and procedures needed to make that happen. This is enormously easier and cheaper to do with spinning disk below a certain level but if you have enough data the lower media cost of tape will balance out the increased overhead.
- garblegarble 13y ago
  > simply leaving an LTO tape on its side can push failure rates to significant levels within a year. Do you have a source for that? I'd not heard of that before, I'm now interested to know what % the failure rate increases by
  - TheCondor 13y ago
    http://www.clir.org/pubs/reports/pub54/5premature_degrade.html http://www.clir.org/pubs/reports/pub54/5premature_degrade.ht... They don't mention the rates though
    - garblegarble 13y ago
      Thanks!
  - acdha 13y ago
    Thank TheCondor for posting something more official. I'd never heard about that before, either (not having had tape storage as a primary job), but a colleague was quite surprised by 20-30% failure rates for tapes first used within a year and asked our drive vendor about it. At the time, there was nothing mentioned on the media we bought and the tape vendor didn't have any official docs but the drive technician we dealt with said that it was well known among the support group - apparently a lot of customers either didn't know or didn't assume it'd be so dramatic.
craigyk 13y ago
Which is why I would build a HD robot that doesn't manipulate the disks, but the connector.
- simonster 13y ago
  You don't even need a robot. The electronics needed to digitally "switch" which disk is connected to the server would be extremely inexpensive. I'm not sure why the original article even considers the idea of a disk drive robot.
- KaiserPro 13y ago
  the connectors are only rated for <1000 insertions. Tape is where its at. The best part about a robot is that you can take things out of a library and move them to a somewhere without power or epic cooling.

skrause 13y ago

> HDDs are not designed for long term archive. They simply fail hard when being moved or switched off for a long time. A single disk certainly is bad for long term archive. But when you have thousands of disks and use multiple copies for all data with some fancy error correction you can still get extremely high reliability, you just need to calculate in the expected failure rate.

KaiserPro 13y ago
High failure == high cost.

acdha 13y ago

> HDDs are not designed for long term archive. They simply fail hard when being moved or switched off for a long time. This is also surprisingly easy to do with tape - simply leaving an LTO tape on its side can push failure rates to significant levels within a year. If you care about data there's no substitute for multiple copies which are regularly verified. The idea that you can leave something on the shelf and expect to reliably read it is a dangerous myth. If you care about archival, build a system with the staffing and procedures needed to make that happen. This is enormously easier and cheaper to do with spinning disk below a certain level but if you have enough data the lower media cost of tape will balance out the increased overhead.

garblegarble 13y ago
> simply leaving an LTO tape on its side can push failure rates to significant levels within a year. Do you have a source for that? I'd not heard of that before, I'm now interested to know what % the failure rate increases by
- TheCondor 13y ago
  http://www.clir.org/pubs/reports/pub54/5premature_degrade.html http://www.clir.org/pubs/reports/pub54/5premature_degrade.ht... They don't mention the rates though
  - garblegarble 13y ago
    Thanks!
- acdha 13y ago
  Thank TheCondor for posting something more official. I'd never heard about that before, either (not having had tape storage as a primary job), but a colleague was quite surprised by 20-30% failure rates for tapes first used within a year and asked our drive vendor about it. At the time, there was nothing mentioned on the media we bought and the tape vendor didn't have any official docs but the drive technician we dealt with said that it was well known among the support group - apparently a lot of customers either didn't know or didn't assume it'd be so dramatic.

craigyk 13y ago

Which is why I would build a HD robot that doesn't manipulate the disks, but the connector.

simonster 13y ago
You don't even need a robot. The electronics needed to digitally "switch" which disk is connected to the server would be extremely inexpensive. I'm not sure why the original article even considers the idea of a disk drive robot.
KaiserPro 13y ago
the connectors are only rated for <1000 insertions. Tape is where its at. The best part about a robot is that you can take things out of a library and move them to a somewhere without power or epic cooling.