ZFS With Gpart partitions

[krad]

On 1 January 2012 11:08, Dan Carroll <fbsd at dannysplace.net> wrote:

> Hello all,
>
> I'm currently trying to fix a suspect drive and I've run into a small
> problem.
> I was wondering if someone can shed some light into how GPart works (when
> using labels for partitions).
>
> My drives are 2Tb WD RE4's, originally the array was using 1Tb Seagate
> drives, and I was replacing about 3 of those a year, but since I migrated
> to the RE4's this is my first problem.
> Here is my setup.
>
>        NAME                 STATE     READ WRITE CKSUM
>        areca                ONLINE       0     0     0
>          raidz1             ONLINE       0     0     0
>            gpt/data0        ONLINE       0     0     0
>            gpt/data1        ONLINE       0     0     0
>            gpt/data2        ONLINE       0     0     0
>            gpt/data3        ONLINE       103   0     0
>            gpt/data4        ONLINE       0     0     0
>            gpt/data5        ONLINE       0     0     0
>          raidz1             ONLINE       0     0     0
>            gpt/data6        ONLINE       0     0     0
>            gpt/data7        ONLINE       0     0     0
>            gpt/data8        ONLINE       0     0     0
>            gpt/data9        ONLINE       0     0     0
>            gpt/data10       ONLINE       0     0     0
>            gpt/data11       ONLINE       0     0     0
>
> errors: No known data errors
>
> The drives are connected via an Areca controller, each drive is created as
> a Pass-Thru (just like JBod but also using the cache and BBU).
> So, my problem began when I tried to replace gpt/data3.
>
> Here is what I did.
>
> # zpool offline areca gpt/data3
> # shutdown -p now
>
> (I could not remember the camcontrol commands to detach a device and
> shutting down was not an issue, so that's the way I did it.)
> Replace the failing drive and re-create the passthru device in the areca
> console.
> power on.
>
> All good so far, except the drive I used as a replacement came from a
> decomissioned server.  It already had a gpart label on it.
> As it happens it was labelled data2.
>
> I quickly shut down the system, took the new drive out, put it into
> another machine and wiped the first few megabytes of the disk with dd.
>
> I re-inserted the drive, recreated the passthrough, powered up and
> replaced the offlined drive.
> Now it's resilvering.
> Currently, my system looks like this:
>
>        NAME                 STATE     READ WRITE CKSUM
>        areca                DEGRADED     0     0     0
>          raidz1             DEGRADED     0     0     0
>            gpt/data0        ONLINE       0     0     0
>            gpt/data1        ONLINE       0     0     0
>            da8p1            ONLINE       0     0     0
>            replacing        DEGRADED     0     0     0
>              gpt/data3/old  OFFLINE      0     0     0
>              gpt/data3      ONLINE       0     0     0  931G resilvered
>            gpt/data4        ONLINE       0     0     0
>            gpt/data5        ONLINE       0     0     0
>          raidz1             ONLINE       0     0     0
>            gpt/data6        ONLINE       0     0     0
>            gpt/data7        ONLINE       0     0     0
>            gpt/data8        ONLINE       0     0     0
>            gpt/data9        ONLINE       0     0     0
>            gpt/data10       ONLINE       0     0     0
>            gpt/data11       ONLINE       0     0     0
>
> The resilvering looks like it's working fine, but I am curious about the
> gpart label.   When I query da8p1 I cannot find it.
> # gpart show da8
> =>        34  3907029101  da8  GPT  (1.8T)
>          34  3907029101    1  freebsd-zfs  (1.8T)
>
> # glabel list da8p1
> glabel: No such geom: da8p1.
>
> It should look like this:
>
> # gpart show da0
> =>        34  3907029101  da0  GPT  (1.8T)
>          34  3907029101    1  freebsd-zfs  (1.8T)
>
> # glabel list da0p1
> Geom name: da0p1
> Providers:
> 1. Name: gpt/data0
>   Mediasize: 2000398899712 (1.8T)
>   Sectorsize: 512
>   Mode: r1w1e1
>   secoffset: 0
>   offset: 0
>   seclength: 3907029101
>   length: 2000398899712
>   index: 0
> Consumers:
> 1. Name: da0p1
>   Mediasize: 2000398899712 (1.8T)
>   Sectorsize: 512
>   Mode: r1w1e2
>
>
> So it seems to me that when I inserted the second drive with a label
> called data2, it wiped the label from the *original* drive.
> ZFS does not seem to care about this.  If the label is simply a label and
> losing it does not alter the user data on the drive, then this makes sense.
>
> I am wondering if I can simply re-label the partition without fear of
> breaking something?  Reading the glabel man page I suspect that it may be
> ok.
>
> -D
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>


Just a not you dont appear to be 4k aligned on this drive. As the drive
capacity is > 1.5 Tb you probably should be. You will also be ashift=9 as
well. This may or may not be a problem for you.