Date: Wed, 7 Oct 2015 22:48:08 -0453.75 From: "William A. Mahaffey III" <wam@hiwaay.net> Cc: FreeBSD Questions !!!! <freebsd-questions@freebsd.org> Subject: Re: The saga continues Message-ID: <5615E62E.6070908@hiwaay.net> In-Reply-To: <alpine.BSF.2.20.1510072118430.74151@wonkity.com> References: <5613CA68.6090909@hiwaay.net> <20151006212741.0e128a23.freebsd@edvax.de> <5614278F.10400@hiwaay.net> <alpine.BSF.2.20.1510062239530.9728@wonkity.com> <56159C14.2070207@hiwaay.net> <alpine.BSF.2.20.1510071814490.74151@wonkity.com> <5615DA5C.6010806@hiwaay.net> <alpine.BSF.2.20.1510072118430.74151@wonkity.com>
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On 10/07/15 22:34, Warren Block wrote:
> On Wed, 7 Oct 2015, William A. Mahaffey III wrote:
>
>> On 10/07/15 19:32, Warren Block wrote:
>>> On Wed, 7 Oct 2015, William A. Mahaffey III wrote:
>>>
>>>>> Please read the warning at the top of that page. The Handbook
>>>>> shows the right way of using gmirror(8). My page on it mirrors
>>>>> GPT partitions, which is likely to be a problem if one of the
>>>>> drives ever fails. If you absolutely have to use gmirror(8) with
>>>>> GPT, use only one partition per drive.
>>>>>
>>>>
>>>>
>>>> Can I partition the drives using '-s MBR', then mirror some of the
>>>> partitions & create '-s BSD' slices inside of those mirrors ?
>>>
>>> Ow, my brain. Why are you simultaneously creating safe data storage
>>> along with ultra-unsafe data storage? What is the end goal?
>>>
>>> Multiple mirrors between drive partitions is potentially dangerous.
>>> Consider that drives often die only a few days or hours apart. Now
>>> think of a two-drive system with multiple mirrored partitions. One
>>> drive has died. Put in a new drive, create the multiple partitions
>>> on it, and add them to the mirrors. All of them start replicating
>>> at the same time, putting a big load on the original still-working
>>> drive. The drive that is the same age as the drive that failed...
>>
>> Creating the safe storage for the system so I could (hopefully) get
>> it rebooted & reconstructed if 1 of the 2 HDD's croaks. If your
>> scenario happens (both HDD's croak almost together, or the 2nd one
>> croaks under the load of replicating), I'm fried anyway. That also
>> argues against any mirroring at all, same thing happens if I mirror
>> both drives as per the handbook.
>
> The difference is that multiple mirrored partitions that are
> replicating at the same time put both drives under lots of head
> contention. It will also make it take much, much longer.
Agreed, naturally I hope to avoid that contingency :-).
>
>>>> Specifically, I would partition each drive into 4 primary
>>>> partitions, /boot, swap, 1 partition to be mirrored & then sliced
>>>> up as per the handbook, & 1 partition to be striped & then sliced
>>>> up ? I would probably mirror /boot as well, if feasible. It seems
>>>> this might comport w/ all of the restrictions & possible meta-data
>>>> conflicts, but I am definitely out of my area, hence the questions.
>>>> TIA & have a good one.
>>>
>>> /boot is a directory in /, the boot partition is just a place to
>>> store bootcode. They are separate things.
>>
>> Agreed, bad nomenclature on my part .... it would be boot-partition,
>> swap, mirrored-partition & striped partition.
>>
>>>
>>> What is the function of the RAID0 here? Can it be replaced with
>>> tmpfs or maybe an SSD?
>>
>>
>> To maximize available space for storing movies, etc. I would be
>> slicing it into 2 slices, for /usr/local & /home. All stuff here
>> would be backed up elsewhere on the LAN and/or recreatable. I just
>> want the largest possible pool of GiB's available.
>
> ZFS with a RAIDZ1 is a reasonable compromise. Three drives instead of
> two, the space of two drives, any one drive can fail but the array
> still works.
>
Only 2 SATA slots on the (mini-ITX) mbd, tight case, not much room for
anything else, thus pretty much stuck w/ 2 HDD's, I think.
--
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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