Date: Wed, 9 Sep 2015 10:27:09 -0453.75 From: "William A. Mahaffey III" <wam@hiwaay.net> To: freebsd-questions@freebsd.org Subject: Re: Storage question Message-ID: <55F04E83.6070902@hiwaay.net> In-Reply-To: <55F04D78.8070508@hiwaay.net> References: <55EF3D23.5060009@hiwaay.net> <20150908220639.20412cbd@gumby.homeunix.com> <55EF5409.8020007@yahoo.com> <55EFC2DA.3020101@hiwaay.net> <08B351DD-AA48-4F30-B0D6-C500D0877FB3@lafn.org> <55F02DC8.7000706@hiwaay.net> <20150909150626.5c3b99e5.freebsd@edvax.de> <55F031A0.40500@hiwaay.net> <20150909145820.c3b48aafad4f70553c1c1fd8@sohara.org> <55F0451A.5080709@hiwaay.net> <20150909160005.d3b84775c3d0748014a871e5@sohara.org> <55F04D78.8070508@hiwaay.net>
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On 09/09/15 10:21, William A. Mahaffey III wrote:
> On 09/09/15 10:06, Steve O'Hara-Smith wrote:
>> On Wed, 9 Sep 2015 09:47:00 -0453.75
>> "William A. Mahaffey III" <wam@hiwaay.net> wrote:
>>
>>> On 09/09/15 09:04, Steve O'Hara-Smith wrote:
>>>> On Wed, 9 Sep 2015 08:23:54 -0453.75
>>>> "William A. Mahaffey III" <wam@hiwaay.net> wrote:
>>>>
>>>>> I like ZFS in principal (it's one of the things that attracted me to
>>>>> FreeBSD about a year ago), but, as someone else noted, it seems to
>>>>> require lots of RAM & possibly CPU for best effect. The MythTV box is
>>>>> an AMD A4-5000, 1.5 GHz quad-core jaguar, w/ 16 GB of RAM, which
>>>>> isn't
>>>> My house fileserver (erm NAS in modern speak) is a dual core
>>>> Atom with 4GB. It manages a 4x2TB RAIDZ2 as well as a bunch of jails.
>>>> According to top it has 2432M for ARC (3592M altogether is wired).
>>>> Memory is tight but it's not swapping, and it doesn't no matter what
>>>> the load. Switching to your spec would be a hefty upgrade and would
>>>> almost certainly make things faster, but then most things can be made
>>>> faster with an extra expenditure.
>>>>
>>>>> especially robusto by today's standards, so I am staying w/ UFS.
>>>>> Someone
>>>> If you have the opportunity then benchmark ZFS and see, if you
>>>> can run it the benefits are great.
>>>>
>>> I am quite amenable to running ZFS, I just don't want to have to
>>> abandon
>>> it & return to UFS if my system proves inadequate for the task,
>>> hence my
>>> caution about it. If I go to ZFS, I (*think* I) use it for the whole
>>> drives, except for swap (possibly), & slice it up into
>>> 'partitions/slices/whatever' to do the install, right ? That was my
>>> take-away from reading the online pages about it. Maybe I need to
>>> rethink ....
>> Yes that's essentially it - you assemble the raw storage you're
>> going to use into a zpool from which the storage that backs the
>> filesystems
>> is drawn automatically. Once you have a zpool making a filesystem is
>> very
>> cheap. The filesystems share the pool, if you want to cap them you
>> can but
>> otherwise they're all limited by the pool. I've never filled a ZFS
>> pool, I
>> don't think I want to.
>
>
> I have heard that filling your zpool is a *BAD* thing, but it can be
> for any FS, just maybe a bit worse for ZFS. I am going to study that
> option a bit more. The online docs all seem to show swap within the
> zpool as well, does that work OK, performance wise ? It would simplify
> installation, however I am planning to script that, so a bit of
> 'extra' effort for separate swap partitions is not an issue. I have
> always thought that separate swap partitions directly kernel managed
> were the best for swap performance if/when it gets down to that, no ?
*Eeeeeeeek*, scratch that bit about 'all show swap under zpool', I was
doing that from memory (last summer), sorry :-/ ....
--
William A. Mahaffey III
----------------------------------------------------------------------
"The M1 Garand is without doubt the finest implement of war
ever devised by man."
-- Gen. George S. Patton Jr.
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