Memory usage

[Den]

I am very new to NAS4Free and have been messing about with it for several weeks on an old P4 PC with 2 GB of ram. After I felt confident that I could set it up and NAS4Free would do what I needed it to do I built a new system.
System specs
Motherboard = Gigabyte GA-78LMT, Socket AM3
CPU = Athlon II X3 450 3.2 GHZ
Memory = 2 X 4GB 1333MHz DDR3
PSU = 500w Cooler Master GX-Lite
HD = 3 x 2TB Western Digital Caviar Green
Case = AVP Triton Mid Tower

This system is to be used to backup several PC's using Acronis True image software. After several tests everything seems to be working fine except when I look in the System information page in NAS4Free the memory usage while idle is using 4% of 2597 MiB. How can this be 2597 when I have 8GB installed. When NAS4Free boots up it shows 2880448 KB of available memory. Using a converter 2880448 KB is about 2.7GB so I am missing about 5GB if I am reading things right. I have checked the motherboards bios and the 8gb is showing as installed. I have done a few test backups and it seems quite fast backing up a 32GB image in about 15 minutes but do I have a problem with the amount of memory NAS4Free is showing in the System information page.
Thanks.

[Onichan]

I think with its current design it wont use large amounts of RAM unless you force it to. You can either use viewtopic.php?f=71&t=1278 to set how much system RAM you have which will change ZFS settings to force large cache or you can manually change them. They are set in /boot/loader.conf and at the bottom you want to either modify or add

vm.kmem_size="30720M"
vfs.zfs.arc_min="28672M"
vfs.zfs.arc_max="28672M"
vfs.zfs.prefetch_disable="1"
vfs.zfs.zil_disable="0"
vfs.zfs.txg.timeout="5"
vfs.zfs.vdev.max_pending="10"
vfs.zfs.vdev.min_pending="4"
vfs.zfs.write_limit_override="0"

Note: mine are currently set with 32GB NAS so you will need to adjust accordingly.

[xuesheng]

Are you using the 32-bit (x86) version of NAS4Free?

You need to use the 64-bit (x64) version of NAS4Free if you want NAS4Free to use all of your RAM.

See viewtopic.php?f=57&t=1306&p=5093

[Den]

Thanks, I was using the 32-bit version that I already had installed on an old P4 2GB system and did not think to upgrade once I had built the new system. 64-bit version now installed and 8 gig of ram now showing in the NAS4Free system information page.
I have timed a backup of a 34 gig system image using both the 32-bit and 64-bit software and both take about 15 minutes even though there is more available ram in the 64-bit system. So what are the benefits of using the 64-bit version of NAS4Free with 8GB of ram over the 32-bit version that has only 3GB of ram available as both version seem to take the same length of time to backup the same size image.

[xuesheng]

ZFS uses a lot of memory, especially if you use any of the advanced ZFS features, so it works best on 64-bit systems which have a lot of RAM.

You can still use basic ZFS features on 32-bit systems with less RAM, e.g. viewtopic.php?f=57&t=1374