Enable reconstruct-write mode

jumperalex · November 27, 2013

Yes the driver would make a determination on a write-by-write basis. So yes, if you were writing a large file, and a daemon spun up all the disks during the transfer, the mode would switch automatically from r/m/w to recon-write.

It would switch in the middle of writing that large file or after that file? I'm just confused by what a "write" means when you say "write-to-write". Is it a file, stripe, block?

In any case, that might be a way to make writing to a only a specific share a recon-write while others stay as rm-writes. Just an idea and I think I've overstayed my welcome. Thanks for indulging me.

nars · November 27, 2013

Driver works at block level then I can only guess yes Tom means it would switch mode at middle of writing a file. I can also tell you that I did some tests yesterday on a tests VM to manually switch mode a few times during a file write (in fact I did stress tested switching it and then doing some data integrity tests) and could easily see it changing the method instantly by looking at virtual hdd's activity "leds".

WeeboTech · November 27, 2013

Driver works at block level then I can only guess yes Tom means it would switch mode at middle of writing a file. I can also tell you that I did some tests yesterday on a tests VM to manually switch mode a few times during a file write (in fact I did stress tested switching it and then doing some data integrity tests) and could easily see it changing the method instantly by looking at virtual hdd's activity "leds".

perhaps we could/should attempt that whole md5sum benchmark test to double check integrity.

nars · November 27, 2013

Driver works at block level then I can only guess yes Tom means it would switch mode at middle of writing a file. I can also tell you that I did some tests yesterday on a tests VM to manually switch mode a few times during a file write (in fact I did stress tested switching it and then doing some data integrity tests) and could easily see it changing the method instantly by looking at virtual hdd's activity "leds".

perhaps we could/should attempt that whole md5sum benchmark test to double check integrity.

Yes, that's a good idea On some quick tests I made I could not find any problems, but I'm sure you can go even deeper than me on stress testing it as I remember you had an even more complex script and a real test system to do it when we tested reiserfs issues.

jumperalex · November 28, 2013

Driver works at block level then I can only guess yes Tom means it would switch mode at middle of writing a file. I can also tell you that I did some tests yesterday on a tests VM to manually switch mode a few times during a file write (in fact I did stress tested switching it and then doing some data integrity tests) and could easily see it changing the method instantly by looking at virtual hdd's activity "leds".

Well now that IS promising indeed.

nars · November 28, 2013

Re-test now with 3 data disks, and writing to empty filesystem on the new disk:

root@unRAID:~# df -h

Filesystem Size Used Avail Use% Mounted on

tmpfs 128M 768K 128M 1% /var/log

/dev/sda1 16G 764M 15G 5% /boot

/dev/md1 1.9T 1.6T 280G 86% /mnt/disk1

/dev/md2 1.9T 452G 1.4T 25% /mnt/disk2

/dev/md3 1.9T 33M 1.9T 1% /mnt/disk3

shfs 5.5T 2.0T 3.5T 37% /mnt/user

root@unRAID:~# ls -latr /mnt/disk3

total 0

drwxrwxrwx 4 nobody users 80 2013-11-28 04:58 ./