It's possible to mount HDD 768 bit/sector (Linux is on 512b/sector HDD).If answer is YES, pls tell me how.

Thanks.

512 bytes (not bit) per sector is not given to you by Linux, it is hardware defined. Some newer drives now use 4KB/sector, but to change it physically to 768 bytes is not possible.

Yes, true, bytes. To be more clear, HDD is formated for 768bytes/sector. It's possible to do (19 page of HDD manual, "Formatting"). I just need to make image of this hdd for cloning later.
Thanks.

I have never done it and I wouldn't recommend it. Also, cloning tools are not aware (and they don't need to be) about the physical structure on the disk, so I doubt that this is necessary in any case.
What exactly are you trying to do?

FYI it is possible to change the sector size which is accomplished by a low level format. Typically a BIOS feature of the SCSI controller. As asked by TobiSGD why?

HDD contains old and specific OS (mpx-32). Hardware (so old to), on which run this specific OS, support only this kind of disk format. There is only one way to make system recovery - magnetic tape. So , to make recovery process faster, need to make disk image for cloning later.

There should be nothing to do. I highly suspect your 768 number includes the sector header and sector checksum. There is no reference to 768 in your document reference. The standard is for 512 byes of data (plus whatever is needed for the sector header and checksum).

The fact you "can't mount" is more likely due to the different filesystem in use, and that is one that Linux doesn't use.

IF all you are going to do is copy the disk to another, use dd on the device file. Something like "dd if=<device> bs=1M of=<image file or the destination device file>".

And make suitable substitutions on the <device> and <image file or the destination device file>.

Thanks ppl. for answer, I'll try .