That is cool, and I might end up doing that with this pool some day.

But is there somewhere where it specifies that the filesystem should be 
mounted read-only?


On Tue, 11 Mar 2014, Linda Kateley wrote:

> Yea it's binary.. Only zfs can read it..
>
> The cool thing is that if you use another server to read the pool, it will be 
> able to build a new cache file for it..
>
> lk
>
>
> On 3/11/14, 6:08 PM, tclug at freakzilla.com wrote:
>> Finally, the expert (:
>> 
>> Yeah, I have an /etc/zpool/zpool.cache, but it seems to be in a (mostly) 
>> binary format rather than an editable text file.
>> 
>> I think last time I rebooted it came up read-write, so maybe that... 
>> resolved itself... which is cool but I wish I had a bit more info on what 
>> the heck was going on!
>> 
>> On Tue, 11 Mar 2014, Linda Kateley wrote:
>> 
>>> So yes zfs caches everything it can in the arc. Most distros have an arc 
>>> max setting or some tunables for arc management. One of the easiest is 
>>> setting primary-cache=metadata, that will tell zfs to only cache metadata.
>>> 
>>> On Solaris there is file in /etc/zfs called zpool.cache. It functions 
>>> similarily to the xxtab files in that if it exists it will be read in at 
>>> boot and contains all device and filesystem info, but it differs in that 
>>> if it doesn't exist it will be built with info from info on disks.
>>> 
>>> Sent from my iPhone
>>> 
>>>> On Mar 11, 2014, at 3:09 PM, tclug at freakzilla.com wrote:
>>>> 
>>>> That's why I was asking (: Someone wake Linda up!
>>>> 
>>>>> On Tue, 11 Mar 2014, Jake Vath wrote:
>>>>> 
>>>>> Call me stupid, but I forgot we were talking about ZFS on Linux... 
>>>>> you're
>>>>> right. No fstab and no vfstab.
>>>>> Sorry about that.
>>>>> -> Jake
>>>>> On Tue, Mar 11, 2014 at 3:01 PM, Jeremy MountainJohnson
>>>>> <jeremy.mountainjohnson at gmail.com> wrote:
>>>>>      Not sure on the distro you have, but with ZFSonLinux you don't
>>>>>      use fstab. For example, in Arch there is a service to handle
>>>>>      this if enabled at boot (part of the zfs package). The file
>>>>>      system mount point is configured with zfs user space tools, or
>>>>>      defaults to what you set originally when you created the volume.
>>>>> Also, curious on the ram problems. Arch, the distro I use, is tweaked
>>>>> to be heavy on caching to RAM. So, often times when I am working with
>>>>> extensive I/O and large files, 90% of memory will be dedicated to
>>>>> caching in RAM and never touch swap (ext4, sw raid1). If I need that
>>>>> cached RAM, it diverts it out of the cache automatically. The free
>>>>> command shows how RAM is allocated. I'm no zfs expert, but perhaps zfs
>>>>> is caching like crazy to RAM, although now that you're stable with
>>>>> more RAM, this kinda debunks that.
>>>>> -- 
>>>>> Jeremy MountainJohnson
>>>>> Jeremy.MountainJohnson at gmail.com
>>>>> On Tue, Mar 11, 2014 at 2:42 PM, <tclug at freakzilla.com> wrote:
>>>>>      Course I'm not using ECC RAM. This is a home system (:
>>>>>
>>>>>      The data is... well, be nice if it didn't get corrupted,
>>>>>      but if a video file gets a small glitch in it, it's not a
>>>>>      huge deal. I can always rerip one disc if I need to. I
>>>>>      also figured that's why I have two smaller raidz1 (which
>>>>>      is equivalent to raid5, right?) pools - it should be able
>>>>>      to fix the occasional checksum error.
>>>>>
>>>>>      I've not seen any crop up on this setup until that scrub,
>>>>>      which was after I copied and erased about 8TB a couple of
>>>>>      times. So not super worried.
>>>>>
>>>>>      I can't really not use the filesystem during a scrub,
>>>>>      since a scrub takes over 24 hours. I could restrict it to
>>>>>      read-only.
>>>>>
>>>>>      Hey, that reminds me, for some reason the thing mounts as
>>>>>      read-only when I reboot. And since it's not in fstab I
>>>>>      don't know where to fix that... anyone?...
>>>>>
>>>>>      On Tue, 11 Mar 2014, Jake Vath wrote:
>>>>>
>>>>>                  Now, I am seeing occasional checksum
>>>>>            errors. I stress-tested the
>>>>>                  heck out of the thing for a week or so
>>>>>            (filled up the
>>>>>                  filesystem, then deleted most the junk I
>>>>>            used for that, etc) and
>>>>>                  when I ran a scrub it found 12 of them.
>>>>>            I'm assuming that since
>>>>>                  I am running multiple redundancies that
>>>>>            that's not a huge
>>>>>                  problem. Is this correct? Should I
>>>>>            cronjob a scrub once a month?
>>>>>
>>>>>            Are you using ECC RAM?
>>>>>            If you're not, then you'll see some
>>>>>            checksumming/parity calculation errors.
>>>>>            Is this a huge problem? I guess it could be
>>>>>            when you consider how important
>>>>>            your data is to you.
>>>>>            Your ZPool(s) could get really screwed up if
>>>>>            you're getting checksumming
>>>>>            errors.
>>>>>
>>>>>            A cronjob to scrub the system isn't a bad
>>>>>            idea, I guess you'd have to make
>>>>>            sure that nothing is going to try and use the
>>>>>            system during the scrubbing
>>>>>            process though.
>>>>>
>>>>>            -> Jake
>>>>>
>>>>>            -> Jake
>>>>>
>>>>>            On Tue, Mar 11, 2014 at 2:24 PM,
>>>>>            <tclug at freakzilla.com> wrote:
>>>>>                  This is a follow-up to my ZFS woes from
>>>>>            a month or so ago.
>>>>>
>>>>>                  Funny thing. When that machine had
>>>>>            16gigs of RAM + 16gigs of
>>>>>                  swap, it was using 15gig of RAM and not
>>>>>            touching swap at all,
>>>>>                  and ZFS performace was horrible.
>>>>>
>>>>>                  So I threw another 16gigs of RAM in
>>>>>            there.
>>>>>
>>>>>                  Now it uses 20gigs of RAM (still not
>>>>>            touching swap, obviously)
>>>>>                  and ZFS performance is fine.
>>>>>
>>>>>                  Now, I am seeing occasional checksum
>>>>>            errors. I stress-tested the
>>>>>                  heck out of the thing for a week or so
>>>>>            (filled up the
>>>>>                  filesystem, then deleted most the junk I
>>>>>            used for that, etc) and
>>>>>                  when I ran a scrub it found 12 of them.
>>>>>            I'm assuming that since
>>>>>                  I am running multiple redundancies that
>>>>>            that's not a huge
>>>>>                  problem. Is this correct? Should I
>>>>>            cronjob a scrub once a month?
>>>>>
>>>>>                  I'm pretty gald I didn't need to move
>>>>>            away from ZFS...
>>>>>
>>>>>                  --
>>>>>
>>>>>            _______________________________________________
>>>>>                  TCLUG Mailing List - Minneapolis/St.
>>>>>            Paul, Minnesota
>>>>>                  tclug-list at mn-linux.org
>>>>> 
>>>>> http://mailman.mn-linux.org/mailman/listinfo/tclug-list
>>>>>
>>>>>      _______________________________________________
>>>>>      TCLUG Mailing List - Minneapolis/St. Paul, Minnesota
>>>>>      tclug-list at mn-linux.org
>>>>>      http://mailman.mn-linux.org/mailman/listinfo/tclug-list
>>>>> _______________________________________________
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>>>>> tclug-list at mn-linux.org
>>>>> http://mailman.mn-linux.org/mailman/listinfo/tclug-list
>>>> _______________________________________________
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