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I am looking at the following two drives for a RAID device, which will be streaming normal things but also a lot of video:

  • Seagate Constellation ES.3 ST4000NM0033 - hard drive - 4 TB - SATA-600
  • TOSHIBA DT01ACA300 3TB 7200 RPM 64MB Cache SATA 6.0Gb/s 3.5"

Will the 128 MB cache on the Seagate have an effect in my described scenario, compared to the 64 MB on the Toshiba? If so, what sort of difference can I expect?

I'm using a qnap device, if that matters.

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Nobody here can tell you whether it's worth your money (except if the more expensive drive is worse in every way, but let's not assume that). You could try asking how to determine which drive is best for your use case instead, not asking for specific models... – Daniel Beck Dec 17 '12 at 18:39
@DanielBeck I thought I did. – johnny Dec 17 '12 at 18:40
I asked for video with the device specifically if 128MB cache was better than 64MB cache in the hard drive. Is it hype or a real difference worth the extra money. – johnny Dec 17 '12 at 18:41
I'm not sure why this was closed... It seems to me to be a legitimate hardware question, i.e. "Does extra HD cache make a difference when streaming video". We can at least present the pros and cons of large caches. He can decide if it's worth the extra cost... – BobT Dec 17 '12 at 18:47
I removed the shopping-related parts from the question, including the prices, to make it purely about the effects of HDD cache. @johnny If you think I removed too much, do feel free to rollback to a previous revision. I also voted to reopen. – Indrek Dec 17 '12 at 19:44
up vote 0 down vote accepted

From what I understand, a hard drive cache is used for stashing frequently accessed information in a fast solid state buffer (cache) on the drive so when that particular data is requested again the drive can pull it out of cache- a much faster process than getting it from the mechanical part of the drive. If you are streaming movies (or video) there probably won't be any performance advantage with a larger cache, since the same data won't be accessed repeatedly. Having said that, all things being equal, there is no downside purchasing a drive with a larger cache, and it might help with some of the smaller 'normal' files you refer to.

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I am reasonably sure that this explanation of what the cache on disk does is incorrect. The drive cache holds IO operations, not frequently accessed data. More cache = more IO ops that can be queued and reported to the OS as completed regardless of whether they were already written to disk. – Reality Extractor Jun 16 '14 at 0:57
I agree with Extractor. I think what Bob is describing would be hybrid 'SSHD' drives that have actual solid state storage for storing frequently accessed information. The SSD on these hybrid drives is typically several Gigabytes in size, and are separate from the actual cache. – Johannes Feb 29 at 23:23

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