Date: Thu, 10 Jun 2010 15:11:12 -0400 From: jhell <jhell@dataix.net> Cc: Alexander Leidinger <Alexander@leidinger.net>, fs@freebsd.org Subject: Re: Do we want a periodic script for a zfs scrub? Message-ID: <4C1138D0.7070901@dataix.net> In-Reply-To: <AANLkTilech-Onkawu4pvNQx5hrByd3R-Mn6MK4AiSHsc@mail.gmail.com> References: <20100609162627.11355zjzwnf7nj8k@webmail.leidinger.net> <4C0FAE2A.7050103@dataix.net> <4C0FB1DE.9080508@dataix.net> <20100610115324.10161biomkjndvy8@webmail.leidinger.net> <AANLkTin445x53XTprCkn1ISmVrnJeSu1XhR52tmtUfkS@mail.gmail.com> <20100610173825.164930ekkryr5tes@webmail.leidinger.net> <AANLkTilech-Onkawu4pvNQx5hrByd3R-Mn6MK4AiSHsc@mail.gmail.com>
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On 06/10/2010 12:34, Artem Belevich wrote:
> You can do something like this:
>
> #SCRUB_TS="2010-06-08.20:51:12"
> SCRUB_TS=$1
> # parse timestamp, move it forward by 1 month and print in seconds since Epoch
> NEXT_SCRUB_DATE_S=`date -j -f "%Y-%m-%d.%H:%M:%S" -v+1m +"%s" $SCRUB_TS`
> # for debugging purposes convert epoch time into something human-readable
> NEXT_SCRUB_DATE=`date -r $NEXT_SCRUB_DATE`
> # surrent time in secs since Epoch.
> NOW_S=`date +"%s"`
> # Compare two times to figure out if next scrub time is still in the future
> if [ $NOW_S -gt $NEXT_SCRUB_DATE_S ]; then
> echo yup.
> else
> echo nope.
> fi
>
> --Artem
#!/bin/sh
lastscrub=$(zpool history exports |grep scrub |tail -1 |cut -f1 -d.)
todaypoch=$(date -j -f "%Y-%m-%d" "+%s" $(date "+%Y-%m-%d"))
scrubpoch=$(date -j -f "%Y-%m-%d" "+%s" $lastscrub)
echo $lastscrub Last Scrub From zpool history
echo $todaypoch Today converted to seconds since epoch
echo $scrubpoch Last scrub converted to seconds since epoch
expired=$((((($todaypoch-$scrubpoch)/60)/60)/24))
if [ ${expired:=30} -ge ${daily_scrub_zfs_threshold:=30} ]; then
echo "Performing Scrub...."
else
echo "SORRY its only been $expired days since your last scrub."
fi
My reasoning for setting expired to have a default value of 30 depended
on whether a pool may have just been created in which a scrub would have
never been performed thus with this value being equal to that of the
default threshold would allow that pool to be scrubbed on the first day
it was created.
I considered just doing ${expired:=${daily_scrub_zfs_threshold:=30}}
which would also allow it to be set to whatever a user set their value
to before the pool was created and adds another layer of redundancy on
that variable in a fail-safe sort of way.
Regards & nice work on this. I just noticed the CFT just after writing
this. but still have a look at the above it may simplify the testing
while providing some fallback for what I stated above.
>
>
>
> On Thu, Jun 10, 2010 at 8:38 AM, Alexander Leidinger
> <Alexander@leidinger.net> wrote:
>> Quoting Artem Belevich <fbsdlist@src.cx> (from Thu, 10 Jun 2010 07:59:46
>> -0700):
>>
>>>> Good idea! I even found a command line which does the calculation for the
>>>> number of days between "now" and the last run (not taking a leap year
>>>> into
>>>> account, but an off-by-one day error here does not matter).
>>>
>>> You can get exactly one month difference by using -v option of 'date'
>>> command to figure out the time/date offset by arbitrary amount.
>>> Combined with +"%s" format to print number of seconds since Epoch and
>>> -r to specify the reference point in time it makes 'date' pretty
>>> useful in scripts.
>>
>> What we have is the date of the last scrub (e.g. 2010-06-08.20:51:12), and
>> what we want to know is if between the last scrub and now we passed a
>> specific amount of days or not.
>>
>> What I do is taking the year multiplied with 365 plus the day of the year.
>> Both of this for the last date of the scrub and "now". The difference is the
>> number of days between those two dates. This value I can use with -le or -ge
>> for the test command.
>>
>> This is only off by one once in a leap year when the leap-day is in-between
>> the two dates (those people which want to scrub every 4 years are off by two
>> when both leap-days are in-between, but a scrub of every 4 years or more
>> looks unreasonable to me, so I do not care much about this).
>>
>> This is done in one line with two calls to date (once for the last scrub,
>> once for "now") and a little bit of shell-buildin-arithmetic. If you have a
>> more correct version which is not significantly more complex, feel free to
>> share it here.
>>
>> Bye,
>> Alexander.
>>
>> --
>> "Who would have though hell would really exist? And that it would be in New
>> Jersey?" -Leela
>> "Actually..." - Fry
>>
>> http://www.Leidinger.net Alexander @ Leidinger.net: PGP ID = B0063FE7
>> http://www.FreeBSD.org netchild @ FreeBSD.org : PGP ID = 72077137
>>
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--
jhell
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