ZFS Few Questions

[list, mailing]

Wow. Great reply.
Going to do some practice with mirror type and 9 RC 2.

Thanks again

On Thursday, November 17, 2011, Freddie Cash <fjwcash at gmail.com> wrote:
> On Thu, Nov 17, 2011 at 10:26 AM, list, mailing <list at sprymed.com> wrote:
>>
>> Hello everyone I just had a few questions about ZFS.
>> I normally use Hardware RAID 5.
>>
>> Question 1:
>>
>> With the ZFS snapshots what is the lost in drive spacoe?
>>
>
> If no data changes after you create the snapshots, then no disk space is
used by the snapshots.
> If data changes after you create the snapshot, then the snapshot holds
the original data.  For example, if you have 100 GB in the filesystem,
create a snapshot, then modify 10 GB of data, the snapshot will hold 10 GB
of data (the original, unchanged data), and the total disk usage
(filesystem + snapshot) is 110 GB.
>
>>
>> Hard drives I have:
>> 4 x 500 GB = 1.5T on RAID 5
>>
>> I have see lots of videos like: ZFS is Smashing Baby
>
> With ZFS, you decide how much disk space you want to use for redundancy.
 With 4 harddrives, you have the following options:
>   2x mirror vdev = 1.0 TB of usable space; best performance, can lose 2
drives before losing data
>   1x raidz1 vdev = 1.5 TB of usable space; decent performance, can lose 1
drive before losing data
>   1x raidz2 vdev = 1.0 TB of usable space; ok performance,, can lose 2
drives before losing data
> raidz1 is similar to RAID5.  raidz2 is similar to RAID6.
>
>>
>> Question 2:
>>
>> FreeBSD 9.0 installable on ZFS root?
>
> Yes.
>
>>
>> Question 3:
>>
>> Anyone Recommend for MySQL server? (Performance)
>
> Read through the ZFS Admin Guide for recommendations for running
databases on top of ZFS.
>
>>
>> Question 4:
>>
>> fsck used with when Server just turns off? (Fast or slower filesystem
check
>> when compared to UFS on HW RAID 5 )
>> Taking note of: "FreeBSD 9.0 adds support for lightweight journaling on
top
>> of softupdates(SU+J), which greatly reduces and need for background fsck,
>> and uses NFS-style ACLs by default."
>>
> ZFS does not have a separate "fsck" tool.  It does not need it.  If the
box crashes, ZFS will just come back online, possibly losing 5-10 seconds
worth of uncommitted data.  If ZFS is unable to come back online
automatically, you can manually roll it back a transaction group or two.
 You'll lose a bit of data, but the filesystems will be coherent and intact
and operational.
> --
> Freddie Cash
> fjwcash at gmail.com
>

-- 
Ben Adams
http://www.SpryMed.com/