Re:Tape still beats SSDs and hard drives when it comes to pr...
by adrian_b on Thursday September 26, 2019 @05:12AM
(#21079389)
> why on earth would you need 25 spare computers for 25 drives??? 25 drives fit into a single 4U chass
I have already mentioned that with other words at the end of my reply and in that case you will not have a speed 25 times higher, but maybe at most 4 times higher than a single HDD, i.e. twice higher than a single tape drive.
Maybe I misunderstood, but the initial posting mentioned a restoring operation from tapes that was slow and my point was that using HDDs is unlikely to make it faster. For a restoring operation the duration will be dominated by sequential transfers, not by seeking, so tape drives would be faster than HDDs, unless you use ridiculous resources, like in my example with a computer per HDD and with a network fast enough to aggregate the data from all computers.
If we are talking about general-purpose data storage on tapes, then obviously, what is frequently accessed should be on SSDs, because the average seek time for a file stored on tape will be between 1 minute and 2 minutes.
I suppose that there might exist applications where there exists a quantity of data so large that it would be too expensive to be stored on SSDs and with worst case latency requirements so severe that it cannot be stored on tapes, so you have to use HDDs. However, in some 40 years of using all kinds of computer systems in many companies, I have never encountered such an application. Everything I have seen could be better handled by a combination of SSDs and tapes, without any HDDs. The only problem with tapes is the prohibitive cost of drives, which limits their use to data sizes of at least 50 to 100 TB, unless long term storage reliability is more important than the cost.
I have already mentioned that with other words at the end of my reply and in that case you will not have a speed 25 times higher, but maybe at most 4 times higher than a single HDD, i.e. twice higher than a single tape drive.
Maybe I misunderstood, but the initial posting mentioned a restoring operation from tapes that was slow and my point was that using HDDs is unlikely to make it faster. For a restoring operation the duration will be dominated by sequential transfers, not by seeking, so tape drives would be faster than HDDs, unless you use ridiculous resources, like in my example with a computer per HDD and with a network fast enough to aggregate the data from all computers.
If we are talking about general-purpose data storage on tapes, then obviously, what is frequently accessed should be on SSDs, because the average seek time for a file stored on tape will be between 1 minute and 2 minutes.
I suppose that there might exist applications where there exists a quantity of data so large that it would be too expensive to be stored on SSDs and with worst case latency requirements so severe that it cannot be stored on tapes, so you have to use HDDs. However, in some 40 years of using all kinds of computer systems in many companies, I have never encountered such an application. Everything I have seen could be better handled by a combination of SSDs and tapes, without any HDDs. The only problem with tapes is the prohibitive cost of drives, which limits their use to data sizes of at least 50 to 100 TB, unless long term storage reliability is more important than the cost.