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I'm using LTFS to transfer 7zip'd files to my LTO6 tapes on a Windows 10 machine with the latest drivers and software. I'm having an issue when writing to the LTO6 drive is maxing out around 70MB/s. Averaging at 63MB/s

I have tried copying over my 1Gbps network stream. I have tried copying from my NVMe SSD locally on the machine.

LTO6 drive is connected via LSI SAS2 2308 Mustang.

I'm new to LTO technology and with LTO6 maxing at 160MB/s, I was hoping for somewhere closer to that number.

Edit:

Copying a single 100GB file from 1TB NVMe SSD

Tape formatted with LTFS Blocksize 524288 (512kB).

Firmware 35BD

Tried compression enabled and disabled

Windows Driver - 1.0.9.3

Ryan Jeremiah Freeman
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1 Answers1

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As you have given the information to your environment (Windows10, LTFS, HP Storage and testing copying via Windows explorer) some common causes for not maxing out top speed:

  • Do not use Windows explorer for speed tests, the way Windows Gui copies is unreliable -> use a command line copy or a dedicated backup SW for tests
  • Anti virus/malware software on the machine/server inhbiting high speed (sometimes 1/2 the speed)
  • small chunks (~up to 512MB) vs large chunks (8 GB)
  • sequential read from a storage device vs. random read
  • reading from a single drive (controller) vs. reading from a raid system, average speed of the device is the limit
  • using a GUI based backup SW (might verify in the background) vs command line batch
  • datapath setting of the storage policy copy you can adjust the block size for writing to a tape. Default is 64k, if you change this to 256k/512k, your throughput should increase.
  • Upgrade firmware of the controller and the LTO device to the latest available (if your LTO device is HP or IBM this is a sure bet)

Checking all this and adjusting accordingly should give you an average minimum of 120MB/s up to 140MB/s

Codebreaker007
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  • There is no AntiVirus running. Unknown as to chunk size. over 1000MB/s SSD read-write speed. Transferring a single 100GB file to the tape drive. Using Windows Explorer to copy using LTFS. – Ryan Jeremiah Freeman May 09 '20 at 13:32
  • Using HP StoreOpen, the Tapes are formatted with Block size of 524288 (512kB) – Ryan Jeremiah Freeman May 09 '20 at 14:55
  • So Windows Defender is disablel and the 1000/MB/s is tested on the OS with a tool (not from the data-sheet). if yes try a copy on the command line to rule out explorer (which will probably be a bottleneck due to the way Windows Gui handles file copies) or test with a dedicated backup tool. – Codebreaker007 May 09 '20 at 16:10
  • Perfect, issue seems to be using Windows Explorer Used TeraCopy and Xcopy and got almost consistently 163MB/s Thank You! – Ryan Jeremiah Freeman May 10 '20 at 01:06