iSCSI Backing store

Dan Nelson dnelson at
Thu Feb 20 20:45:29 UTC 2014

In the last episode (Feb 20), Steve Burton said:
> I'm trying to familiarize myself with the iSCSI implementation in FreeBSD
> 10 REL.  I have made a target containing two LUNs which are backed by two
> files on my test server (redundant PC).  This all worked well though it
> took ages to make the files using dd.
> dd if=/dev/zero of=/targets/target0-0 bs=512 count=31250000
> My first question is, is there a better and quicker way to make the
> backing store files?

A 512-byte blocksize is suboptimal; you're spending most of your time just
processing the read/write syscalls at that size.  There isn't much benefit
to using a blocksize over 64k, but using 1m does make it easy to calculate
the count for large volumes :)
> My second question relates to making iSCSI LUNs using a disk volume.  I
> have a second (empty) hard drive.  Is it possible to just use the disk as
> backing store for iSCSI?

I don't see why not.  

	Dan Nelson
	dnelson at

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