SAS controller for LTFS in Windows 10

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mactsk

New Member
Jul 10, 2023
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Hi,
i have a windows 10 pc with DELL perc H200 and an IBM Lto6 drive
It works but i suspect the controller is a bottleneck, i only transfer zip/tar files (quite big) but sometimes the copy slows down, and almost never exceeds 150/180 mb/s
I bought an used Dell Adaptec PCI-E 12Gb SAS Controller ASR-8885, it sees the LTO drive but it can't read the tape, and when i try to format it says it can't do since the blocksize is not correct, i tried to hunt it down but it seems that the block size can''t be changed
Someone can tell me if there is a recent controller (better with some cache RAM) that works well with LTFS and Windows 10?

Thanks!
 

Stephan

Well-Known Member
Apr 21, 2017
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Germany
Check Wikipedia for LTO speeds. LTO-6 is 160 MByte/sec for already compressed data like ZIPs. Perc H200 is SAS2008 so a bit older chipset but still can do 6 Gbps which is about four times the LTO-6 speed for a single SAS lane. Not any bottleneck and other controller will gain you nothing imho. Upgrade to LTO-8 would get you close to 300 MB/sec or above, with same controller.

It is normal for LTO drives to take a couple minutes before reaching full speed when you first insert a new tape. Tape will be rewound slower on very first pass to measure read and/or write quality and also to relieve any non-homogenous strain in material from storage. This will lead to half speed or worse. Should go away after a couple minutes and with large files drive should write 160 MB/sec.

Never used LTFS myself but with normal tape software maximum performance is reached with a maximum block size of 1 MB and a maximum file size setting of 20 GB. Look here: https://www.bareos.com/whitepapers/optimizing-the-tape-speed.pdf Maybe you can tweak something a little.
 

mactsk

New Member
Jul 10, 2023
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1
Thanks, I thought that it was a controller issue (and partly is) because I use 3 1tb ssd in raid 0 as a cache drive to store data to write/read on the lto an noticed it makes a similar speed when I expected 300+ megabytes speed, so I bought the other controller.