Set I/O block size

You must also consider I/O block size before creating a ZFS store this is not something that can be changed later so now is the time. It’s done by adding the –b 64K to the ZFS create command. I chose to use 64k for the block size which aligns with VMWare default allocation size thus optimizing performance. The –s option enables a sparse volume feature aka thin provisioning. In this case the space was available but it is my favorite way to allocate storage.

(Note we use 64k also for formatting the disk in windows so it makes sense to use the same blocksize here)

zfs create -b 64K -V 1800G dawpool/backup

Resilvering

The process of replacing a drive can take an extended period of time, depending on the size of the drive and the amount of data in the pool. The process of moving data from one device to another device is known as resilvering, and can be monitored by using the zpool status command.

Traditional file systems resilver data at the block level. Because ZFS eliminates the artificial layering of the volume manager, it can perform resilvering in a much more powerful and controlled manner. The two main advantages of this feature are as follows:

*

ZFS only resilvers the minimum amount of necessary data. In the case of a short outage (as opposed to a complete device replacement), the entire disk can be resilvered in a matter of minutes or seconds, rather than resilvering the entire disk, or complicating matters with “dirty region” logging that some volume managers support. When an entire disk is replaced, the resilvering process takes time proportional to the amount of data used on disk. Replacing a 500-Gbyte disk can take seconds if only a few gigabytes of used space is in the pool.
*

Resilvering is interruptible and safe. If the system loses power or is rebooted, the resilvering process resumes exactly where it left off, without any need for manual intervention.

To view the resilvering process, use the zpool status command. For example:

# zpool status tank
pool: tank
state: DEGRADED
reason: One or more devices is being resilvered.
action: Wait for the resilvering process to complete.
see: http://www.sun.com/msg/ZFS-XXXX-08
scrub: none requested
config:
NAME STATE READ WRITE CKSUM
tank DEGRADED 0 0 0
mirror DEGRADED 0 0 0
replacing DEGRADED 0 0 0 52% resilvered
c1t0d0 ONLINE 0 0 0
c2t0d0 ONLINE 0 0 0
c1t1d0 ONLINE 0 0 0

In this example, the disk c1t0d0 is being replaced by c2t0d0. This event is observed in the status output by presence of the replacing virtual device in the configuration. This device is not real, nor is it possible for you to create a pool by using this virtual device type. The purpose of this device is solely to display the resilvering process, and to identify exactly which device is being replaced.

Note that any pool currently undergoing resilvering is placed in the DEGRADED state, because the pool cannot provide the desired level of redundancy until the resilvering process is complete. Resilvering proceeds as fast as possible, though the I/O is always scheduled with a lower priority than user-requested I/O, to minimize impact on the system. Once the resilvering is complete, the configuration reverts to the new, complete, configuration. For example:

# zpool status tank
pool: tank
state: ONLINE
scrub: scrub completed with 0 errors on Thu Aug 31 11:20:18 2006
config:

NAME STATE READ WRITE CKSUM
tank ONLINE 0 0 0
mirror ONLINE 0 0 0
c2t0d0 ONLINE 0 0 0
c1t1d0 ONLINE 0 0 0

errors: No known data errors

The pool is once again ONLINE, and the original bad disk (c1t0d0) has been removed from the configuration.

Setup ZFS iSCSI

Created an array
bash 3.2# zpool create daw c1t1d0

root@dawbkup:~# zfs set shareiscsi=on daw
root@dawbkup:~# zfs get shareiscsi daw

NAME PROPERTY VALUE SOURCE
daw shareiscsi on local

zfs create -V 120G daw/backup
[any zvols (not filesystems, I checked) created under daw will automatically become LUNs]

Ignore the following eror Probably caused by the fact I forgot to import from categorie Storage the "storage-san" package
root@dawbkup:~# zfs set shareiscsi=on daw/backup
cannot share 'daw/backup': iscsitgtd failed request to share

zfs set shareiscsi=on daw/backup

root@dawbkup:~# iscsitadm list target -v

Target: daw/backup
iSCSI Name: iqn.1986-03.com.sun:02:aa46a269-bef7-4432-9ed2-9890738fc784
Alias: daw/backup

After this I downloaded the Iscsi Initiator for windows XP and used the instructions from Microsoft. At the end the volume is shown when you go to My computer -> Manage -> Disk management. You now can create partitions add drive letters and format just like a regular disk within Windows.