LTO8 and blocksizes

[lowlander]

Hi,

We are using LTO8 tapes. Values currently to choose for blocksize are 65536 - 131072 - 262144 - 524288 - 1048576. Currently using 262144 is resulting in a back-up to tape performance of approximately 300 MBps.

Any advice on why using other ( higher or lower values ) than the current default setting 262144, regarding optimal write performance to tape ? ( Or maybe other aspects )

[HannesK]

Hello,
https://en.wikipedia.org/wiki/Linear_Tape-Open

Wikipedia makes me think that 300MByte/s you see is pretty near to the theoretical speed limit of LTO8. I'm not sure what to optimize there. 524288 would be nearer to Veeam block size... so you can try it out, but I don't expect massive change.

I assume that you run V11 on proper hardware that can deliver the speed?

Best regards,
Hannes

[lowlander]

Correct, we are running V11. I am aware of the limit of throughput regarding LTO8, however am interested in why there are higher numbers available to choose from. I will try if it makes a difference when selecting higher values, however also like to know why for example 1048576 is an option.

Thanks !

[Dima P.]

Hm, if I remember correctly the highest possible value is reported to Veeam B&R by the tape device itself (and is used automatically) but we left the selection available for old devices that do not have this logic. Will double check.