noatime for SSD?

northrnchimp · Jul 12, 2011

Just got an OWC Mercury Extreme installed, and it's a great improvement, but I've read a few articles about how important it is to minimise the number of writes being done to an SSD (to ensure longevity). In OS X the file system keeps track of every time a file is accessed, and updates the file info accordingly. That's a lot of writing, which some say is unnecessary.

Apparently the 'noatime' function can be added to the OSX file system to disable this function. Does anybody know if this is useful, or which apps might be impacted by 'noatime' on the file system? Has anyone tried it?

Lifeisabeach · Jul 12, 2011

northrnchimp said:
Just got an OWC Mercury Extreme installed, and it's a great improvement, but I've read a few articles about how important it is to minimise the number of writes being done to an SSD (to ensure longevity). In OS X the file system keeps track of every time a file is accessed, and updates the file info accordingly. That's a lot of writing, which some say is unnecessary.

Apparently the 'noatime' function can be added to the OSX file system to disable this function. Does anybody know if this is useful, or which apps might be impacted by 'noatime' on the file system? Has anyone tried it?

This is the first I've heard of this, and my most immediate concern was how it may impact Time Machine operations. I just did some reading, and apparently this IMPROVES the speed of Time Machine backups because it doesn't update all those file access times. I'm not reading of any practical downsides to using noatime at all. I may well give this a go myself.

harryb2448 · Jul 12, 2011

Just ignore the 'some say'. Do not disable anything the drive came with. If you are still concerned after lifeisabeach's advice, go to OWC chat technical forums and seek their input.

http://eshop.macsales.com/Service/ts_email.cfm

chas_m · Jul 13, 2011

OWC drives are sold with their own kind of TRIM support so this entire discussion is a complete non-issue.

Lifeisabeach · Jul 13, 2011

chas_m said:
OWC drives are sold with their own kind of TRIM support so this entire discussion is a complete non-issue.

Just so we're clear that we aren't all talking about 2 different things… what you are saying is that what TRIM does is enable noatime? Or at least is part of what it does?

BrianLachoreVPI · Jul 13, 2011

lifeisabeach said:
Just so we're clear that we aren't all talking about 2 different things… what you are saying is that what TRIM does is enable noatime? Or at least is part of what it does?

I think that there is a slight shift in the conversation suddenly. The 'TRIM' support OWC drives come with is related to wear leveling and memory block management. The OP's question is related to the limited number of R/W cycles that is inherent to SSD drives and how to minimize that by limiting unnecessary write activities.

northrnchimp · Jul 13, 2011

Do not disable anything the drive came with

I'm not attempting to disable anything the drive came with - this is about changing the file system in OSX.

Thanks BrianLachoreVPI, you've clarified the issue at least.

northrnchimp · Jul 14, 2011

I guess no-one has tried it then? Well in that case I'll try it out and report back... (after updating my clone of course)

harryb2448 · Jul 14, 2011

For what it is worth, OWC technicians advise most strongly against cloning SSD's as they use different system to platter drives and cloning can cause problems. Recommended clean system install from disc, use Migration Assistant to transfer applications, network settings etc over, and then updating via the Combo Updater.

northrnchimp · Jul 24, 2011

Having spoken to an OWC support tech, he stated that OSX will clone over to an SSD fine, it's Windows which has problems due to sector alignment issues which OSX doesn't have. And having enabled noatime on the filesystem I can confirm there have been no problems whatsoever, Time Machine still works fine etc. And my SSD will now last a bit longer

Lifeisabeach · Jul 24, 2011

northrnchimp said:
Having spoken to an OWC support tech, he stated that OSX will clone over to an SSD fine, it's Windows which has problems due to sector alignment issues which OSX doesn't have. And having enabled noatime on the filesystem I can confirm there have been no problems whatsoever, Time Machine still works fine etc. And my SSD will now last a bit longer

Thanks for the heads-up. I never got around to enabling it myself since I don't have an SSD and won't till my next upgrade. Good to know that it's working out. I do want to point one thing out. Lion now has the option to sort folder contents by "Date Last Opened". I would think that enabling noatime would defeat the ability to rely on this option if one wanted to use it.

randalthor · Jul 24, 2011

I've enabled noatime on my mac because I too am running an ssd. I haven't had any issues with it, and time machine backups do seem to be a little smaller. I've also restored from time machine backups made with noatime enabled, and no glitches. so i say go for it.

noatime for SSD?

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