Re: large scale (audio) file I/O on OS X : help or insight requested
Re: large scale (audio) file I/O on OS X : help or insight requested
- Subject: Re: large scale (audio) file I/O on OS X : help or insight requested
- From: Hamilton Feltman <email@hidden>
- Date: Wed, 11 Mar 2015 18:36:57 -0700
Hi Paul,
It’s an external StarTech raid enclosure with Mac OS Extended Journaled. Did I say raid 0? It’s not raid 0, it’s mirrored (raid 1), so the performance should be like a single drive. It’s the only spinning disk I tested.
What is the speed of the drive you tested? This script will give an accurate figure:
#!/bin/sh dd if=/dev/zero bs=1024k of=_tstfile count=1024 2>&1 | awk '/sec/ {print $1 / $5 / 1048576, "MB/sec write" }' sudo purge dd if=_tstfile bs=1024k of=/dev/null count=1024 2>&1 | awk '/sec/ {print $1 / $5 / 1048576, "MB/sec read" }' rm _tstfile
It would be nice if you included the printf in readtest.c: printf ("seeks: %llu: bytes: %llu total_time: %f\n", cnt * nfiles, (nfiles * _read), total_time/1000000.0);
so we can pinpoint where the time is being spent.
Regards, Hamilton
On Mar 11, 2015, at 9:11 AM, Paul Davis < email@hidden> wrote:
We just got around to trying with both F_RDAHEAD and F_NOCACHE. They seem to make no difference at all on the one system we tested. http://pastebin.com/ZKjVA94tI also just noted that your successful test was on "External 3GB WD Reds on USB 3 in raid 0" - what filesystem was on the drives? Do I assume you have no spinner that isn't part of a RAID?
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