Question How much of a difference does the cache of a HDD make?

[Ailurophile]

I'm building a new editing PC. Motherboard is a Gigabyte AORUS Master X570. The system drive with Windows 10 will be on a NVMe PCIe4 1TB. I need to build a new RAID while utilizing the X570 raid capability so it will be a RAID10 configuration with 4x HGST Ultrastar 6TB 7200rpm 128MB cache drives. This raid will be used as storage for 4K/6K/8K video editing projects.

I'm finding fast mechanical drives to still be more expensive than I would have anticipated in 2019. So I found a good deal on slightly older HGST drives that are unused/brand-new, with a smaller cache (128MB) than the current standard for fast enterprise HDDS (which seems to be 256MB). I know HGST has been EOL'd by Western Digital, and HGST/WD have always been my preferred HDD manufacturer.

So the question is this: How much of a compromise did I make in getting 6TB HDDs with only 128MB caches for a RAID10 setup? Does it effect write speeds more than reading? Would I notice any performance improvement had I gone with 256MB cache drives? Is it more, or less, of an issue in a RAID10 setup?

I searched this forum and couldn't find any topics on this issue. Your thoughts appreciated.

 

[Billy Tallis]

The cache will have minimal effect on sequential access speeds, which should be most of your IO when working on video.

 

[Ailurophile]

The cache will have minimal effect on sequential access speeds, which should be most of your IO when working on video.

Thank you for sharing your knowledge.

For posterity's sake for some future person in a similar scenario & build predicament- I am not overly concerned about write speeds because more often than not the client provides media in a less than optimal speed external enclosure. At the time of this writing that would be USB3.0 Which is great, but obviously convenience always seems more tantamount than best transfer rates. Especially since Thunderbolt v1/2/3 is not widely enough adopted and seems on its way out. So offloading from the provided external USB3 media is usually a set-it-and-forget-it overnight copy from-to transaction, and that's good enough for now.

 

[00Logic]

If your read data is USB 3 (2 too) and large files; you an increase speed ~30% by increasing the block size of USB data transfers. A larger transfer length reduces protocol overhead, leaving more 'bandwidth for data.

The easiest way to do this is with an app I am quite proud of as I brought the tweak's existence to the attention of USB guru; Uwe Sieber, who then wrote it.
USBSTOR MaximumTransferLength:

Drive Tools for Windows

NB that this block size should be less than or equal to the average file size being transferred.
ie: A 2MB block size will be slower for ~512KB files.

The app above, on that page; USB-WriteCache, is also very handy for writes as Windows only pretends to enable a write cache for any file system besides NTFS.
ie: If the USB drive is formatted exFAT or FAT32 etc. there is no write cache, even if you have enabled it in Device manager.
This app fixes that and adds another ~1MB/s to writes on my USB2 thumb drive.

It also does wonders for a 32GB - exFAT, USB 3 Readyboost cache.
(NB that the stock 64KB Transfer length is best for Readyboost's 4K reads, if anyone still cares)

Then there's UASP,
a SCSI protocol that does wonders for USB 3, (TRIM for a start)
if everything in the chain supports it...
TomsHardware has a good writeup if you're interested.

 

[Ready4Droid]

Good tips, I don't do enough transfers for USB to have looked into this stuff, but now that I know about I'll check it out!