SOLVED Random reboots.. mystery

[toyebox]

results!


[Matt@freenas /mnt/RAID_10/Storage]$ dd if=/dev/zero of=tmp.dat bs=2048k count=50k
51200+0 records in
51200+0 records out
107374182400 bytes transferred in 25.701024 secs (4177817280 bytes/sec)
[Matt@freenas /mnt/RAID_10/Storage]$ dd if=tmp.dat of=/dev/null bs=2048k count=50k
51200+0 records in
51200+0 records out
107374182400 bytes transferred in 13.726569 secs (7822361220 bytes/sec)


yes compression is on..

 

[nightshade00013]

Create a dataset with compression turned off. With DD you are writing a file that is HIGHLY compressible and it will give skewed results.

I would expect it to be in the 300 to 350 MBps range

 

[toyebox]

nice. thanks so much. i'm pretty disappointed with that 234 MB/s write speed :(

[root@freenas /mnt/RAID_10/test]# dd if=/dev/zero of=tmp.dat bs=2048k count=10k
10240+0 records in
10240+0 records out
21474836480 bytes transferred in 91.761795 secs (234028078 bytes/sec)
[root@freenas /mnt/RAID_10/test]# dd if=tmp.dat of=/dev/null bs=2048k count=10k
c10240+0 records in
10240+0 records out
21474836480 bytes transferred in 69.740002 secs (307927099 bytes/sec)

 

[nightshade00013]

Add another pair if you like but honestly if you are using a regular gigabit ethernet cable it won't do much good. My system has 7 drives in a raidZ3 and I can get around 500MBps writes internally but it doesn't do a ton of good for ethernet transfers. I do have some files I transfer on the server between datasets though so I set a script to move them automatically rather than using another computer to be limited by ethernet speeds. It also helps with plex scans and syncthing scans to be much faster.

 

[toyebox]

Add another pair if you like but honestly if you are using a regular gigabit ethernet cable it won't do much good. My system has 7 drives in a raidZ3 and I can get around 500MBps writes internally but it doesn't do a ton of good for ethernet transfers. I do have some files I transfer on the server between datasets though so I set a script to move them automatically rather than using another computer to be limited by ethernet speeds. It also helps with plex scans and syncthing scans to be much faster.

thanks for the reply. yeah I figured if I extended that pool speeds will increase. I fully saturate the gigabit connection as it is but I planned on doing some aggregation in the future.

question about adding drives... I couldn't find it anywhere.. when you add drives to an existing pool with data, is the data moved and spread out? or does that last set of mirrors you add (striped mirrors I'm talking about) start filling before the others.

 

[Mirfster]

FreeNAS will balance new data written to the drives, but a couple caveats (based solely on my *understanding*):

1. Data "At rest" (files that do not change) will tend to stay on the vDev(s) it was originally written to
2. New data will more than likely be written mostly to the new vDev(s) since they have more free space, but for redundancy some will still be spread to existing vDev(s)
3. When free space is roughly equal between vDevs then it will be spread in a more even manner

Of course there are ways around this, like if you have enough space you could make a new dataset and copy all the data there, delete the contents of the old dataset and then copy/move it back so it gets re-distributed again... or something along these lines...

 

[toyebox]

that's how I figured it worked.. I love the idea about the new dataset.. can we get confirmation that will work? what impact do you think it would have on the pool to utilize that other 20% that you shouldn't fill, in order to copy to the new dataset?

thoughts being... copy 20% at a time(assuming you have 80% full of data), delete the old 20% of data you copied, repeat.

 

[SweetAndLow]

If your pool is that full I wouldn't worry about copying stuff around. But it will rebalance the data across all vdevs.

Sent from my Nexus 5X using Tapatalk

 

[toyebox]

I was speaking hypothetically. I am at about 60%. man I'm getting all my questions in!

one more! is there any recovery of data if you happened to lose an entire mirror out of the pool?

 

[SweetAndLow]

No recovery if you lose a vdev.

Sent from my Nexus 5X using Tapatalk

 

[toyebox]

I kept reading over and over... use mirrors instead of raidz2... still the correct path I assume? I am strictly using it for movies/tv/downloading

edit: I am currently using a striped pool with two mirrored vdevs each 4tbs

 

[Mirfster]

I kept reading over and over... use mirrors instead of raidz2... still the correct path I assume? I am strictly using it for movies/tv/downloading

Depends on your Use-Case. There is always a choice the System Owner needs to decide upon between Space, Redundancy and Speed. Each vDev has its own pluses and minuses which you will have to weigh.

Have a read of these to get more info:
cyberjock's: Hardware recommendations (read this first)
cyberjock's: Slideshow explaining VDev, zpool, ZIL and L2ARC for noobs!

 

[SweetAndLow]

Depends on what you need to do.

Mirros are great for vm's if you need performance, they are great if you want to add more drives later and cost is an issue. you will be able to add them in sets of 2. Resilver times are faster with mirrors.

raidz2 is great if you want capacity. Performance will still be good for streaming workflows but random IO will not be as good as mirrors. z2 has good protection and longer rebuild times. if you want to add more disks you should add them in the same vdev size as your your current vdev so that can be more expensive because you will have to buy just as many drives.

My setup is for light vm's usage, media streaming and storing my daily documents I use. I have 2 vdevs with 8 disks each in raidz2.