I came across an interesting use case for FreeNAS.  My eldest daughter likes games that are huge.  Like 100-250 gigabyte huge.  I simply cannot afford to keep adding SSD storage to her machine.  I will not do hard disks as main storage..under Windows 10 it’s too painfully slow.  What Lawerence had done was taken a FreeNAS machine, sliced off a portion of the raw storage, and presented it to the workstation as a hard drive over his network.  His son now run his large games from the FreeNAS zvol as if it was local.  What’s neat is the games initial load time is a bit slower(the NAS is hard drive based) but once it’s loaded..there’s no perceptible difference in gaming performance despite a constant stream of data from the server…usually less than 150 megabit/sec.  Since I have multi Terabytes of free space i am doing the same thing for my eldest.  I am also doing what is called thin provisioning so it initially starts at zero usage and goes up until she reaches her cap of 1 Terabyte.  Let’s see how this works as my quad core Xeon cpu is light years faster(with 4 times more ram at 32 gigabytes) than his FreeNAS mini dual core atom and 8 gigs of ram.  If this works…i have a new idea for future computer builds here at the house..<G>

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  1. […] I made an earlier post about an experiment I am running.  So far so good.  The eldest is having to put her games onto the new G drive her computer sees.  The magic of ISCSI makes it appear as a local hard drive even though it’s on a network server.  I did notice that the transfer was maxing out at 650 megabit/second…i know that the machine can do better..it used to do 2 gigabits/second when it was a backup target.  I wondered what has changed throughout the years?  I did a little bit of digging.  ZFS is all about data safety.  You have to be extremely determined to make it loose data for it to have a chance to do so.  sometimes that ultimate safety comes at the price of performance.  I started looking at the numbers and i noticed ram(32 gigs) was not a problem.  Cpu usage was less than 20% max.  The disks however were maxed out.  Well it turns out that ZFS has a ZIL(ZFS Intent Log) that is always present.  If there is no ZIL SSD then it’s on the main drives.  i thought that double(or in this case triple) writing to the drives was it…but nope..no there.  I had to dig deeper and dug into the actual disk I?O calls.  It turns out that the default setting for synchronous writes defaults tot he application level.  If the application says you must write synchronously…that means zfs will not report back that the write transaction was completed until ti does both of it’s copies and verifies them on the array.  Loosely translated if you were to put this in RAID terms it would be a write-through.  Since ZFS is a COW filesystem I am not concerned about data getting corrupted when written..it won’t(again unless you have built it wrong, configured it wrong…something like that)…so I found a setting and i disabled the forcing of synchronous writes.  I effectively turned my FreeNAS into a giant write-back caching drive.  Now the data gets dumped onto the FreeNAS server’s ram and the server says “i have it” and the client moves on to the next task..either another write request or something else.  Once I did that the disks went from maxing out at 25% usage to nearly 50% usage and the data transfers maxed out the gigabit connection.  That’s how it is supposed to be. […]

  2. […] *Game Cache Update* Is the built in compression.  For vm’s you can sometimes get 5-10x compression because vms are mostly empty space.  ZFS does compression transparently.  Right now as part of the eldest’s game cache her system thinks it has written 75 gigabytes of data.  ZFS compression has reduced that down to 52.5G in the background.  this is roughly a 1.41x reduction in size just form basic compression.  Normally with my file types(movies, music..mainly stuff that is already compressed) I do not see any real compression.  With her steam apps the compression is much higher.  It will be interesting to see if it goes up or down as she loads up the rest of her games. […]

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