Chris Espinosa
blturnerThinking I could image a 2GB SCSI disk running on the Mac II was a bit ambitious... after letting it run all night it wasn't even 1% complete #MARCHintosh
theirongiant@ben - don't use the "compressed" option when making a backup. It's not necessary. Do a read-only or read-write image. It will go significantly faster.
Bruce Elrick@ben Hmmm...
My recollection from the late 90s was that base SCSI was 5 MB/s although most disks couldn't saturate the bus. But 1 MB/s was certainly doable so I'd expect 2 GB to be copyable in under an hour, at least if sequentiality.
My recollection from the late 90s was that base SCSI was 5 MB/s although most disks couldn't saturate the bus. But 1 MB/s was certainly doable so I'd expect 2 GB to be copyable in under an hour, at least if sequentiality.
@virtuous_sloth I'll run some benchmarks after the data is backed up
@ben I'm confused, which may be because I'm doing my math wrong.
2 GB / (1 MB/s) = 2000 s or just over half an hour, which contradicts the 1% overnight figure.
The other possibility is the copy was doing random small-block reads. 6 ms seek translates into around 160 IOPS (1 s / 6 ms = 167). If it was all 512 B blocks, then you'd be getting 80 kB/s. 2 GB / (80 kB/s) = 2000000/80 s = 25000 s, or 10+ hours.
So 30 minutes to 10 hours min/max. I wonder if it was getting a lot of errors?
Curious!
@ben Regardless, glad it finished!
Ken McLeod@ben Like @theirongiant said, this is all down to using the compression option in Disk Copy. A read-only (uncompressed) image will be orders of magnitude faster to create.
@_the_cloud @theirongiant restarted the image without the compression and it's going fast now! 👍