Slow VM disk access on Qemu/SIMH or other emulators running on Windows?

Turns out from an interesting thread on the SIMH mailing list, is that the Windows volume shadow copy service, and other ‘system’ protecting services may tag files like .dsk to be monitored, and to save a difference of every write to the file.

Yes that is right, on top of NTFS’s transaction log and rolls, you have the OS doing the same thing which in turn makes your disk access slower than hell.

The fix?

Quite simple, dont use TLA (three letter acronym) file extensions, or no extensions at all and suddenly you’ll find that your disk based emulation is significantly faster.

This entry was posted in qemu, random updates, SIMH by neozeed. Bookmark the permalink.

About neozeed

What is there to tell? I’ve loved UNIX like things since I was first exposed to QNX in highschool (we had the Unisys ICONS!), and spent the better time of my teenage years trying to get my own UNIX… I should have bought Coherent in retrospect.. Anyways latched onto Linux in 1992, and then got some old BSD admin books and have been hooked on the VAX BSD & other big/ancient things since…!

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