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Krause Krause is offline
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Default SSD Tweaks on Mac? - 07-08-2009, 11:38 AM

Would just like to confirm if any of you guys out there tried this out... got this from another forum...

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Okay, so just to prove I am not just a grumpy old naysayer, here are some things you could do to actually improve performance under OS X.

1) Disable Adaptive Hot File Clustering

This is a feature of the OS that tracks how often files are used and automatically moves them closer to the outer rim of the drive (which is faster on conventional disks). On an SSD it is just a useless block move.

2) Disable automatic defrag

This actually might not be a win, because the system only performs auto defrag in very limited cases (files less than >20 megs with more than 8 extents), and while defragging the file itself will not be a performance win, consolidating its metadata into the file record (so you don't have to walk through the extents btree) might in fact be a win even on an SSD because it significantly reduces the amount of reads you have to do figure out where the file is.

The unfortunate thing is that there is no simple way to do either of these. You could build a custom kernel (it is a ~1-2 line change to short circuit them out). I suspect that neither is going to be a particularly large win though, so you are better off just running a stock (supported) kernel.
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mfruit mfruit is offline
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Default 07-08-2009, 07:18 PM

How 'bout journaling? Is that bad for SSDs? I've seen a couple of articles that claim it's better to run on a non-journaling FS when on SSDs.
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reflex reflex is offline
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Default 07-08-2009, 07:49 PM

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Originally Posted by mfruit View Post
How 'bout journaling? Is that bad for SSDs? I've seen a couple of articles that claim it's better to run on a non-journaling FS when on SSDs.
The reason some people recommend against journaling is that journaling causes more writes, and writes are what wears out flash memory. Personally, I don't think it's a problem. EVERYTHING wears out faster if you actually use it, conventional hard drives included.


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Krause Krause is offline
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Default 07-09-2009, 12:47 AM

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Originally Posted by reflex View Post
The reason some people recommend against journaling is that journaling causes more writes, and writes are what wears out flash memory. Personally, I don't think it's a problem. EVERYTHING wears out faster if you actually use it, conventional hard drives included.
So does this mean disabling journaling would extend the lifepsan of an SSD drive?
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Eligos Eligos is offline
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Default 07-09-2009, 10:51 AM

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Originally Posted by Krause View Post
So does this mean disabling journaling would extend the lifepsan of an SSD drive?
Either way, your SSD should last ~5 years with normal daily usage. By that time your mini will be no longer or you will pony-up for a new faster SSD.


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Krause Krause is offline
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Default 07-18-2010, 11:50 PM

is it possible to create symlinks from the items in /private/var/folders/ (or even the /tmp/ folder) to a ramdisk to save on writes?


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grassle grassle is offline
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Default 07-19-2010, 09:08 AM

I found this*, a plist to go into /Library/LaunchDaemons/ that claims to turn access time recording off. Haven't tried it yet.

* Google translation
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Krause Krause is offline
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Default 07-19-2010, 12:18 PM

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Originally Posted by grassle View Post
I found this*, a plist to go into /Library/LaunchDaemons/ that claims to turn access time recording off. Haven't tried it yet.

* Google translation
also have that one... has anyone tried to modify it to mount mac's counterpart of tmpfs to /tmp/ or /private/var/tmp/ ?


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Previously:
Mini 9  Obsidian Black  BIOS: A05  16GB SSD  2GB RAM  Webcam: 1.3 MP  BT: On  Legacy USB: Off  Snow Leopard 10.6.2  NBI/NBM 0.83  iWork '09  iPhoto '09  iMovie '09  Photoshop CS4  Soundbooth CS4
Mini 9 Obsidian Black BIOS: A05 16GB SSD 2GB RAM Webcam: 1.3 MP BT: On Legacy USB: Off Snow Leopard 10.5.8 NBI/NBM 0.83MSO 2K8 Aperture 3.03
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grassle grassle is offline
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Default 07-19-2010, 04:28 PM

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Originally Posted by Krause View Post
also have that one... has anyone tried to modify it to mount mac's counterpart of tmpfs to /tmp/ or /private/var/tmp/ ?
Nope. Gave up as I've not even got this one to work -- a script to maintain /var/log/* in tmpfs and write it to disk on shutdown.

Noobnesse oblige.
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