So initially I setup my unRAID box 4.4.2 without a parity drive (I have 2x1TB drives I wanted to use so that expanding capacity would not be an issue).  I have data on 1 of the 1TB drives, so I installed the blank on in the system and started it without parity, copied all the files over to the unRAID box... worked great, got 40-60MB/s over a gigabit network... loved it. 

 

Now, i have setup my system adding extra drives I had laying around and the 1TB for parity.  Installed easy, ran the Parity Sync/Check or whatever, to get parity started (took several hours but the we interface said it ran at like 50+MB/s, so thought that was good).

 

Now the sad part... I have the system running, and have now started to move files over to it... I am getting 4MB/s -30MB/s in spiking intervals... Watching TOP on the box, i see smbd spike, then drop as the unraid process kicks up (although still never goes above 7-8%, where the smbd goes to 30%+ in spikes).

 

What is causing this?  Is it due to the parity drive being on the same controller? (I assume same, but don't know... tech specs to follow). ??

 

System Specs:

- 2 GHz Celeron dual core (E1400)

- on a Foxconn Motherboard G31MX-K Intel G31 LGA775 - ICH7 SATA Controller

- 2GB (2x1G 800 ddr2) ram

 

HD Stats/Tests

 

Status Disk Mounted Device Model/Serial Temp Reads Writes Errors Size Used %Used Free

OK parity /dev/sdc WDC_WD10EACS-00D6B0_WD-WCAU40384147 23°C 243151 3137862 0

OK /dev/md1 /mnt/disk1 /dev/hda WDC_WD2500JB-00GVA0_WD-WCAL72365143 27°C 691633 80 0 250.05G 34.29M 1% 250.02G

OK /dev/md2 /mnt/disk2 /dev/sda WDC_WD10EAVS-00D7B1_WD-WCAU46190122 21°C 2606462 4148 0 1.00T 884.39G 89% 115.78G

OK /dev/md3 /mnt/disk3 /dev/sdb ST3320620AS_5QF4CJLP 26°C 1157668 229154 0 320.06G 55.84G 18% 264.22G

OK /dev/md4 /mnt/disk4 /dev/sdd Maxtor_6Y080M0_Y2421H2E 24°C 625806 86 0 81.96G 33.63M 1% 81.93G

 

 

/dev/sdc: Parity

Timing cached reads:  2394 MB in  2.00 seconds = 1197.08 MB/sec

Timing buffered disk reads:  268 MB in  3.01 seconds =  88.94 MB/sec

 

/dev/sda:

Timing cached reads:  2462 MB in  2.00 seconds = 1231.07 MB/sec

Timing buffered disk reads:  264 MB in  3.01 seconds =  87.72 MB/sec

 

/dev/sdb:

Timing cached reads:  2410 MB in  2.00 seconds = 1205.51 MB/sec

Timing buffered disk reads:  232 MB in  3.02 seconds =  76.70 MB/sec

 

/dev/sdd:

Timing cached reads:  2398 MB in  2.00 seconds = 1199.27 MB/sec

Timing buffered disk reads:  170 MB in  3.01 seconds =  56.40 MB/sec

 

/dev/hda:

Timing cached reads:  2402 MB in  2.00 seconds = 1201.35 MB/sec

Timing buffered disk reads:  174 MB in  3.03 seconds =  57.41 MB/sec

 

Need any other info?

 

Thanks for any and all help!

 

Marc

 

Are you using Vista?

 

Are you using Vista?

 

 

Yes... but I used it to move the files before the Parity drive was installed and it ran at 60MB/s... so why the change, and why right after I enabled Parity?  (I use TeraCopy to copy files and get my speed values).

This is normal.

 

The way parity works, each logical write to the array requires 2 reads and 2 writes on the array disks as follows.

 

1.  The existing sector on the data disk is read

2.  The corresponding sector on the parity disk is read

<unraid is now able to recompute parity based on the new sector data>

3.  The new sector data is written to the data disk

4.  The updated parity is written back to the parity disk

 

With buffering it is common to have it appear to wildly fluctuate.  The average varies a bit, but usually is between 8-12 MB/sec.  Some have reported speeds as high as 14-15 MB/sec.

 

If you install a cache disk, you will be able to write to that disk faster and should get speeds similar to what you got to the array before parity was installed.  Then, overnight, when you're not waiting on the array, unRAID will automatically move the data to your array.  This was LimeTech's partial solution to the write performance issue, and works well for many users.

 

Please take the time to read the FAQ, Best of the Forums, and Troubleshooting wiki pages (see links in my sig).  This topic is well covered, as well as many other topics that will answer a ton of questions you haven't thought to ask yet!

 

Good luck!

I misread the OP... I though it was Mbps, not MBps.

 

Yes, about 1 GigaByte per minute is going to be your top end with parity enabled, unless youa re using a cache disk.

Thanks for the quick and great responses... I promise I did read the forums using search... although I admit I forgot about the FAQ 

 

As for a cache disk... I have see that in a number of posts, so hopefully I can find where it tells you how to enable one (I don't see it in the web interface on my unRAID box).... if your bored and want to help me be lazy, please post links to how to setup one

 

Thanks!!!

Forgot one other question... Would speed be increased if I moved the Parity Disk to another Controller (installed an SATA card specifically for the parity drive)??

Ok... back again... I read the "best of the boards" about cache disk support, and see mention that it is only available to the Pro version!?  WHAT THE... not very nice... I hope that changes in the NEAR future...

That may be changing ... see this post.

 

BTW, you can pretty easily install a DIY cache disk.  I did that before the cache disk feature was even offered.  The limitation is that it wouldn't be a part of user shares.

 

I personally do not use user shares and have my own methods to move data from cache to the array.

 

Forgot one other question... Would speed be increased if I moved the Parity Disk to another Controller (installed an SATA card specifically for the parity drive)??

 

No.