[OpenIndiana-discuss] SSDs for OI hipster ZFS root mirror?

[Richard L. Hamilton]

Seems like the Linux style O_NOATIME flag (usable only by root - or on Solaris derivatives, possibly with a fine-grained permission) might be a useful addition to the OS, so that system programs that read a lot of files can avoid causing massive time updates that either generate excess I/O and obscure meaningful atimes, or have one mounting with the noatime option that makes them useless entirely.

Needless to say, programs like pkg would have to be modified a bit to use it on whatever they opened read-only that they didn't want to cause the atime to be updated on.

I think there are some things like old fashioned style mail directories where one really needs atime updates; and over and above forensics or similar situations, there are a fair number of other cases where it might be useful, such as to find and possibly get rid of unused files in certain directories.

> On Aug 21, 2021, at 07:36, Peter Tribble <peter.tribble at gmail.com> wrote:
> 
> On Sat, Aug 21, 2021 at 10:32 AM James <list at xdrv.uk> wrote:
> 
>> On 19/08/2021 23:58, Carl Brewer wrote:
>>> Further to this - is it worth disabling atime on the ZFS root pool
>>> that's on the SSDs? I don't imagine it's a lot of data, but it would add
>>> up over the years.
>> 
>> Do you ever look at the access times?
>> 
> 
> On some occasions, this is very useful - you can work out what
> software installed is actually in use, and it's a way of detecting
> unexpected things running.
> 
> We turn it off at $WORK because of two things - we run pkg
> verify every night, which means the access times are meaningless
> because we read every file daily anyway, and we hold a lot of
> regular snapshots and the atime writes end up consuming a significant
> amount of snapshot space.
> 
> -- 
> -Peter Tribble
> http://www.petertribble.co.uk/ - http://ptribble.blogspot.com/
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