What's causing all that disk I/O on my Mac?

| Posted: - Last updated:
| Tagged osx mac disk-io troubleshooting
| ~300wrds (~1min)

After doing a full re-install of my MacBook Pro a few weeks back to combat system slowness, I’m again struck with a slow system.

The problem is that there’s a lot of disk I/O going on. CPU and memory are fine. I’m just not sure what’s causing this trouble.

Luckily, there’s an easy solution to find out what’s doing disk I/O on you mac.

Open up a terminal and run

$ sudo fs_usage
09:08:45.749208  read              F=12   B=0x400                                                                     0.000210 W Sparrow.3845544
09:08:45.749274  lseek             F=12   O=0x0602e000         <UNKNOWN>                                              0.000002   Sparrow.3845544
09:08:45.749279  read              F=12   B=0x400                                                                     0.000005   Sparrow.3845544
09:08:45.749341  lseek             F=12   O=0x06038c00         <UNKNOWN>                                              0.000002   Sparrow.3845544
09:08:45.750358    RdData[async]   D=0x025aaf38  B=0x1000     /dev/disk0s2                                            0.028830 W Sparrow.3845547
09:08:45.750379  pread             F=16   B=0x30       O=0x00b32730                                                   0.028895 W Sparrow.3845547
09:08:45.750390  pread             F=16   B=0x30       O=0x0de9a810                                                   0.000008   Sparrow.3845547
09:08:45.750396  pread             F=16   B=0x30       O=0x1f5ec5c0                                                   0.000006 W Sparrow.3845547
09:08:45.750399  pread             F=16   B=0x30       O=0x236c84a0                                                   0.000003   Sparrow.3845547
09:08:45.750405  pread             F=16   B=0x4b       O=0x236c84b6                                                   0.000002   Sparrow.3845547
09:08:45.750701  pread             F=16   B=0x30       O=0x00c95f00                                                   0.000007   Sparrow.3845547
09:08:45.758502    RdData[async]   D=0x04f0b608  B=0x1000     /dev/disk0s2                                            0.009148 W

What you see here is Sparrow doing mad reads ot my disk. I’m not sure what it’s doing, but it must stop. After killing Sparrow disk I/O goes down to normal, workable levels again.

Now, to pick another mail client for Mac…

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