Using GTP and glabel for ZFS arrays

[Dan Langille]

On 7/23/2010 10:51 PM, Dan Langille wrote:
> On 7/23/2010 10:42 PM, Daniel O'Connor wrote:
>>
>> On 24/07/2010, at 11:55, Freddie Cash wrote:
>>> It's theoretical as I have not investigated how to create sparse
>>> files on FreeBSD, nor have I done this. It's based on several
>>> posts to the zfs-discuss mailing list where several people have
>>> done this on OpenSolaris.
>>
>> FYI you would do.. truncate -s 1T /tmp/fake-disk1 mdconfig -a -t
>> vnode -f /tmp/fake-disk1
>>
>> etc..
>>
>> Although you'd want to determine the exact size of your real disks
>> from geom and use that.
>
>
> $ dd if=/dev/zero of=/tmp/sparsefile1.img bs=1 count=0 oseek=2000G
> 0+0 records in 0+0 records out 0 bytes transferred in 0.000025 secs
> (0 bytes/sec)
>
> $ ls -l /tmp/sparsefile1.img -rw-r--r-- 1 dan wheel 2147483648000
> Jul 23 22:49 /tmp/sparsefile1.img
>
> $ ls -lh /tmp/sparsefile1.img -rw-r--r-- 1 dan wheel 2.0T Jul 23
> 22:49 /tmp/sparsefile1.img

Going a bit further, and actually putting 30MB of data in there:


$ rm sparsefile1.img
$ dd if=/dev/zero of=/tmp/sparsefile1.img bs=1 count=0
oseek=2000G
0+0 records in
0+0 records out
0 bytes transferred in 0.000030 secs (0 bytes/sec)

$ ls -lh /tmp/sparsefile1.img
-rw-r--r--  1 dan  wheel   2.0T Jul 23 22:59 /tmp/sparsefile1.img

$ dd if=/dev/zero of=sparsefile1.img bs=1M count=30 conv=notrunc
30+0 records in
30+0 records out
31457280 bytes transferred in 0.396570 secs (79323405 bytes/sec)

$ ls -l sparsefile1.img
-rw-r--r--  1 dan  wheel  2147483648000 Jul 23 23:00 sparsefile1.img

$ ls -lh sparsefile1.img
-rw-r--r--  1 dan  wheel   2.0T Jul 23 23:00 sparsefile1.img
$


-- 
Dan Langille - http://langille.org/