3 ms·
> When tape is being read it is streamed over the head at a speed of about 15 km/h... It did say that. I wonder if there's some multi-track/double-layer/double
by LeifCarrotson 6y ago
> When tape is being read it is streamed over the head at a speed of about 15 km/h...
It did say that. I wonder if there's some multi-track/double-layer/double-sided stuff going on that needs multiple passes to read, that does sound awful fast!
- texse 6y agoMost recent tape standards have multiple "bands" and "wraps" placed in parallel. The head reads only one wrap at a time, so it takes many passes to read the whole tape. For example an LTO-8 tape has 52 wraps each within 4 bands, requiring 208 passes to read completely.
- TedDoesntTalk 6y agoWhy not just have multiple heads then?
- nine_k 6y agoPositioning the tape should become harder, I suppose. Also, I suppose they limit the read bandwidth with something like what a single Infiniband connection would support; few disk arrays support much higher speeds.
- paulmd 6y agoIt would be like downloading a file using GetRight back in the day, where you'd have one thread downloading the 0-25% chunk, one downloading the 25-50% chunk, and so on. You could hypothetically do that, for sure, but the software basically is derived from the tape era where you'd just have one logical stream coming out of the tape.
- Dylan16807 6y agoThere are. The tradeoff of speed vs. complexity is currently sitting at 32 heads.