#278 iscsi target files do not reduce diskspace

[Carsten Hammer]

It seems that iscsi target files are created as files "with holes" and do not reduce the diskspace. This is not so good. I currently use freenas via nfs and iscsi connected to a esx server 3 to get an impression of performance. I created a 150GB iscsi target on a partition of 200GB. Both are connected to the esx server via nfs and iscsi at the same time. Now I see 350GB free space on the ESX Server. Every time I write something on the iscsi target the size of the nfs target decreases. freenas should create a target file as one monolithic file at creation time reducing the free space immediatly. This would prevent fragmentation problems too.

[Jerome Warnier]

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I personally feel this as a feature, not a bug. It is really cool to have disk space dynamically assigned to the one really using it.
Maybe a checkbox (not checked by default) saying "Preallocate disk space now" at creation time could make you happy too?

[Carsten Hammer]

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I cannot see any use of this feature in my environment. The ESX Server handles disk shortage very reliable (no loss of data, vmware images are suspended when no disk space is free) if it can rely on what the disk or iscsi device reports back. But as long as this report is wrong I guess what happens is undefined.
However I could live with an option to preallocate disk space. This would help to reduce disk fragmentation as well.
And it might help to prevent bad computation of iscsi disk size that currently is difficult to do right.

[Jerome Warnier]

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I vote for it too: a "preallocate disk space now" checkbox would be welcome when creating an iSCSI target.

[Volker]

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Does not see this feature in the used iSCSI Target software so there is no way to add this.