4 ms·

> LTFS offers an abstraction layer so that software can treat a tape drive like a hard drive. That makes programming easier, but it will not have any effect on

by astine 14y ago

> LTFS offers an abstraction layer so that software can treat a tape drive like a hard drive. That makes programming easier, but it will not have any effect on performance. Ugh. You're more right than you know. This is a misconception that I sometimes have to deal with at my work. Tape systems are not harddrive systems and can't be treated as such even if you use LTFS or an HSM. The problem is that even though you can delete things by removing them from the (disk based) inode table, you can't actually remove them from tape or overwrite them without a special effort, which means that you can't simply reclaim tape space. Being able to access a tapes with the standard API used for HDDs is convenient but you can't lose awareness of the underlying system or you'll screw things up mightily.

acdha 14y ago
I have severe misgivings about HSMs for this reason: too often, they're simply making an API promise which can't be kept. The vendors have an incentive to low-ball the expensive spinning disk component of an HSM to maximize the apparent cost savings but without extensive application suppor that will be a disaster.
- astine 14y ago
  Think of HSM as a more convenient alternative to a traditional tape system, rather than a cheaper alternative to a disk system. I think the benefits outweight the costs, but only if you understand the limitations. Have a guy on staff who understands tape and near-line storage and you should be in a good position. Also, stay away from DiskXttender. I've used that product and it's terrible.
  - acdha 14y ago
    The main problem is that you need to add proprietary HSM interfaces to every application which uses much data. I'd be happier if that was standardized.
  - acdha 14y ago
    The main problem is that you need to add proprietary HSM interfaces to every application which uses much data. I'd be happier if that was standardized.

by astine 14y ago

acdha 14y ago

I have severe misgivings about HSMs for this reason: too often, they're simply making an API promise which can't be kept. The vendors have an incentive to low-ball the expensive spinning disk component of an HSM to maximize the apparent cost savings but without extensive application suppor that will be a disaster.

astine 14y ago
Think of HSM as a more convenient alternative to a traditional tape system, rather than a cheaper alternative to a disk system. I think the benefits outweight the costs, but only if you understand the limitations. Have a guy on staff who understands tape and near-line storage and you should be in a good position. Also, stay away from DiskXttender. I've used that product and it's terrible.
- acdha 14y ago
  The main problem is that you need to add proprietary HSM interfaces to every application which uses much data. I'd be happier if that was standardized.
- acdha 14y ago
  The main problem is that you need to add proprietary HSM interfaces to every application which uses much data. I'd be happier if that was standardized.