iSCSI Enterprise Target

• Immer ScsiSN und ScsiId setzen (evtl. auf die ersten 16 Zeichen der LV UUID)
• Eventuell Type=blockio verwenden

In blockio mode, it defines a mapping between a "Logical Unit Number" <lun> and a given block device <device>. 
This mode will perform direct block i/o with  the device,  bypassing  page-cache for all operations. 
This allows for efficient handling of non-aligned sector transfers (virtualized environments) and large block transfers (media servers). 
This mode works ideally with high-end storage HBAs and for applications that either do not need caching between application and  disk or need the large block throughput.

• Eventuell eine Kombination aus Type=fileio und IOMode=wb testen

Setting IOMode to "wb" will enable write-back caching.
Please note that this could lead to data loss e.g. in case of power outages,
so it is strongly recommended to use an UPS when enabling write-back caching.

Immer deadline verwenden

cat /sys/block/<device>/queue/scheduler
echo deadline > /sys/block/<device>/queue/scheduler

Verringern der Latenz zur Steigerung des Durchsatzes:

• Disable TOE if enabled, you can also try disabling TSO as well.
• options e1000 InterruptThrottleRate=1,1

1. Unmount the volume on the initiator, if needed.
2. Logout and delete the node on the client initiator, so it's no longer accessed.
3. On your fileserver, delete the LUN from the target using ietadm (ietadm –op delete –tid=X –lun=Y). You don't need to delete the whole TID, just the affected LUN. You get this information from /proc/net/iet/volume.
4. Expand/modify/whatever the underlying volume on the server.
5. Dynamically add the LUN back: ietadm –op new –tid=X –lun=Y –params Type=fileio,Path=/dev/foo/bar
6. On the client initiator, add the node again and log back in.
7. You may then need to resize the volume on the client with resize2fs or something similar.