Hello everyone I just watched the video on LinusTechTips about 100tb at over 1gbs. Awesome video, can I get lime tech to come over and give me a helping hand like him? I have been using unraid for awhile now. Love the ease of use. Unraid 6 is amazing, more stuff than I will ever need. My system is a old HPxw8600 workstation. It has 2 Xeon CPUs [email protected], 16 gb of ecc ram,1 3tb parity drive, and 4 2tb drives, and also a LSI sff-8087 mini sas. Nothing ground breaking, just that when ever I start any transfer of files it starts out great, then drops down two about 80mbps. Does this sound right? I bought the sas controller thinking it would help, no change at all. Besides buying a new system is there any device I could purchase that would keep it consistent. Maybe a 4 port Ethernet card, or a fast cache disk? I had freenass on here and I had much better write speed, but freenass is two complicated for me. I am use to unraid anyway, but is there anything reasonably priced that would make the write speed performance more consistent. Any help is much appreciated.

Due to how parity works, writes to the protect array with modern disks usually between 60 and 75MB/s, there are 2 options to have better write speed:

 

1-enable turbo write, much faster at the expense of having all disks spin up for writes

2-use a cache disk

As Johnnie noted, there are two ways to improve your write speed, as he outlined.

 

Note that turning on Turbo Writes really increases the speed of the writes, since the data is actually being written to the array.  This helps because there are no longer 4 disk operations required to do a write [read disk being written to; read parity disk; then write the data and updated parity back to those 2 disks];  Instead, it simply reads all of the data disks while writing the new data to the disk being written to; then writes the updated parity information to the parity disk.  More actual disk operations, but no latency delay while the disks spin an entire revolution ... which the "normal" method requires.

 

Using a cache increases the "perceived" write speed ... and is actually faster than Turbo Write ... but since the data is only cached, it's NOT on the protected array and is "at risk" until a later time when the "Mover" moves the data to the protected array [These writes won't be any faster than normal, but will be done at a time that you're not otherwise using the array].  If your cache happens to be a btrfs array, it will have some protection ... but most are not.

 

Thanks for the responses, I didn't know about the turbo writes. I just have tried a clean install with the latest beta and a weird thing happened it would start a parity check, but would not format any of the hard rives.I then started to try another clean install after using partition magic to wipe the drives and also reformat all of the hard drives. This time all but one hard drive has formated I left it like that and I have only 45 minutes till the parity is done. Any reason this would happen? When parity is done I am going to try and wipe the hard drive again. I think that is just weird. Hopefully after I get parity finished, get the drive format and back into the system, and use the tips you have given I will be good to go. Thanks again.

Any reason this would happen?

 

It can happen when the disks have previous files systems, there are to ways to fix it, using the preclear script to completely wipe the disks or clicking on each the disk and changing filesystem to XFS (or whichever one you're using) instead of auto.

BTW, turbo write is actually called "reconstruct write", it can be enable on Settings -> Disk settings -> Tunable (md_write_method):

johnnie.black I tried that on the old install. And I also did that on the new install. The default file system (auto) as far as I know is xfs so when I used partition magic to clear and format the drives I format them to btfrs making sure when I did the new install if would have to format the drives again from btfrs to xfs. I said I have 4 2tb drives and it shows the total amount as being 8tb even when it says that the one drive is unmountable. Don't understand it.

Tools -> Diagnostics

 

Upload zip.

Okay thanks you a lot.

Well I can't fix the format issue. It shows I have 8tb on both the server and my windowshare. But the reconstruct write works like a charm. It seems rock solid. But the format issue will drive me crazy. Anyway its performs better than ever 112 mbs rock solid.

Here it. "Tools -> Diagnostics

 

Upload zip."

tower-diagnostics-20160810-0920.zip

Try this:

 

stop array, click on disk4, on "File system type:" change from auto to XFS, start array, if disk is still unmountable click format.

LOL you are amazing worked instantly. I am not smart enough to even as you the right questions on how you figured that out from the attachment. Thanks so much really.

unRAID is detecting more than um filesystem on that disk, that's why auto doesn't work, there's no problem leaving it like that, set to XFS, but you need to remember that if at any time in the future you do a new config you need to do the same thing, or the disk will again appear as unmountable.

Will do, broken record here but thanks again, I got the consistent speed, and all formats are correct. Everything is working perfectly. Seems like to me the turbo write would be a default setting since it makes such a dramatic difference. Anyway awesome!!!

... Seems like to me the turbo write would be a default setting since it makes such a dramatic difference. ...

 

One of the nice features of UnRAID is that it does not require all of the array drives to be spun up for normal operation.  A standard write only spins up 2 drives (3 on 6.2 if you have dual parity) => the drive being written to, and the parity drive(s).

 

The turbo write features requires that ALL drives be spun up.    A lot of folks don't want this ... especially those with large arrays of 20+ drives.    They either accept the "normal" write speed; or simply use a cache drive, which provides very fast "perceived" write speeds ... and simply moves the data to the array at a later time (typically in the middle of the night).

 

Cache drive is on my list for sure. I guess then I should turn turbo write back off?

Cache drive is on my list for sure. I guess then I should turn turbo write back off?

 

No real reason to turn it off => just depends on whether or not you mind having all of your drives always spinning when you're doing any writes.

 

BTW, turbo write is actually called "reconstruct write", it can be enable on Settings -> Disk settings -> Tunable (md_write_method):

 

I'm trying to get faster writes to my unRAID system too, but I don't have the Tunable (md_write_method): option. As fas as Tunables, all I have is:

 

Tunable (poll_attributes): 1800

Tunable (md_num_stripes):1280

Tunable (md_sync_window):384

 

BTW, turbo write is actually called "reconstruct write", it can be enable on Settings -> Disk settings -> Tunable (md_write_method):

 

I'm trying to get faster writes to my unRAID system too, but I don't have the Tunable (md_write_method): option. As fas as Tunables, all I have is:

 

Tunable (poll_attributes): 1800

Tunable (md_num_stripes):1280

Tunable (md_sync_window):384

Depending upon your version of unRaid, you may not have the ability to adjust the md_write_method via the GUI.  You can either do it via the command line, or you can install the user scripts plugin and then look in the thread for additional scripts for it, and there are a couple of scripts that deal with turning off / on turbo mode.