I've been playing with unRAID for a few days with different hardware and now i'm in the process of rebuilding pairty.  I thought that i'd done this before going from a little 80gb ide drive to a 250gb sata drive.  I dont remember how long it took or how the system performed while it was happening. I dont think i had much data there at the time. I now have... maybe 80~100gb there and i've switched from a 250gb sata to a 320gb ide parity drive and it's saying that it's going to take a couple of days to rebuild.  Is that normal? 

 

It's going at 1,960 KB/sec.  Just out of curiosity I killed the process and went back to the 250gb sata drive and when that started it was working at about the same speed. 

 

This 320gb drive is only temporary until i get my RAID5's data coped to unRAID then i plan to put in a 500GB sata parity drive.  I'd really rather not have it take days to rebuild.

 

I've also noticed that while it's building parity that while the system looks to be available the performance makes it unusable for watching video.

 

Can someone confirm that this are operating as intended?

Speed is largely dependent on how old the drive is.  A newer drive shouldn't take that long, but older ones will.  My rebuild with five 300GB SATA IIs took a few hours at a rate of ~30+MBps.

 

I suggest doing two things:

 

1. Tell us your configuration - be specific, including any BIOS settings you made, version of unraid, hardware, ...

2. Attach your syslog

 

 

Bill

I've been playing with unRAID for a few days with different hardware and now i'm in the process of rebuilding pairty.  I thought that i'd done this before going from a little 80gb ide drive to a 250gb sata drive.  I dont remember how long it took or how the system performed while it was happening. I dont think i had much data there at the time. I now have... maybe 80~100gb there and i've switched from a 250gb sata to a 320gb ide parity drive and it's saying that it's going to take a couple of days to rebuild.  Is that normal? 

 

It's going at 1,960 KB/sec.  Just out of curiosity I killed the process and went back to the 250gb sata drive and when that started it was working at about the same speed. 

 

This 320gb drive is only temporary until i get my RAID5's data coped to unRAID then i plan to put in a 500GB sata parity drive.  I'd really rather not have it take days to rebuild.

 

I've also noticed that while it's building parity that while the system looks to be available the performance makes it unusable for watching video.

 

Can someone confirm that this are operating as intended?

No, what you are seeing it is not the normal performance.

 

The duration of a full calculation of parity is dependent on three things:

 

1. The size of your data drives.  (regardless of how many files you have stored on them)  Bigger drives will take longer than smaller drives.

 

2. The number of data drives.

 

3. The mode used to access the data drives.

 

SATA drives are typically two to three times faster than IDE drives.

 

Any drive operating with UDMA modes is *way* faster than the same drive operating in a PIO mode.

Upon enncountering an error, the disk drivers in Linux will retry using a slower access mode.  In other words, even if the drive should support UDMA access, it will revert to PIO mode if errors occur.

 

I typically get about 15,000 to 17,000 KB/sec on my all IDE based array with 8 data drives.  My largest drives are 500Gig. A full parity calc takes 5 to 6 hours.

 

Your 1500 Kb/sec indicates you are running in PIO mode.  Usually, this is a drive with errors, or a bad cable to a drive, or a incorrect BIOS setting on your motherboard forcing PIO mode to be used.

 

New "round" cables are often the cause of this type of error.  Use of an older 40 conductor IDE cable instead of a 80 conductor cable will also cause the errors and the slowdown.  (80 conductor cables usually have a blue, a black, and a grey connector.  The blue should go to the connector on the motherboard)  If all the connectors on your cable are the same color, it is an older 40 conductor cable.

 

An SATA based array when running well will probably do its full parity calc in 3 hours or less.

 

If you are running your SATA drive in IDE Emulation mode in your BIOS, it is likely it is the cause of your lack of speed.  Or, perhaps the cable you now used for your larger IDE parity drive is the issue.  You probably want some kind of SATA enhanced mode enabled in the bios

 

No matter what, a parity calc should NOT take days.

 

Joe L.

Ah HA!!!!!

 

The problem has to be one of two things.... I noticed that when my system is running that one of my drives (one that i just added) reports one error.  Another thing, i just installed two 36" round IDE cables! 

 

Is there anyway to telnet into the box to see the PIO mode? I guess i'll try some different IDE cables. 

 

Thanks a ton for the info. 

Ok i'm back with new knowledge now.

 

 

Just in case someone else in the future discovers this thread i'll mention this:

 

If you telnet into your unRAID box you can see the drive mode by typing:

 

hdparm /dev/hdg

 

*Note* "hda" is the name of one of my hard drives.  You can see these names in the web interface under the devices tab.

 

Ex:

pci-0000:02:00.0-ide-1:0 (hdg) ata-WDC_WD2000JB-00EVA0_WD-WMAEH1240094

 

Once you run the command you will see results like this:

 

/dev/hdg:

multcount    = 16 (on)

IO_support  =  0 (default 16-bit)

unmaskirq    =  0 (off)

using_dma    =  0 (off)

keepsettings =  0 (off)

readonly    =  0 (off)

readahead    = 256 (on)

geometry    = 24321/255/63, sectors = 390721968, start = 0

 

And as you can see... DMA is indeed disabled on this drive.

 

Now comes the part where i ask for help.  I'm 99% sure that DMA works on other drives using these cables and using this IDE card... could it be that my hard drive is not properly supported? When i get home i'll try to move it to a different card just to check it. I guess it's possible that the cable is bad on that one channel?

 

I've tried using:

hdparm -d1 /dev/hdg

 

To enable DMA mode on this drive but no love.  It accepts it but if you check it afterward it's still set to off. 

 

Anyone got any other bright ideas?

 

What really stinks is that if it is indeed the drive... i have four of that i intended to use with unRAID

 

 

 

Oh and here is more info on using hdparm.  It does all kinds of stuff.

 

http://gentoo-wiki.com/HOWTO_Use_hdparm_to_improve_IDE_device_performance

 

Ok so I've discovered that if i stop unRAID and manually set the DMA mode to enabled it comes on and stays on, set to UDMA5 but as soon as i start unRAID DMA mode goes off.  And the transfer rate is abysmal.

 

I really hope that these drives are usable in unraid... pretty scary seeing that they are not.  I wonder if this is a beta bug?

 

BTW, i used

 

hdparm -i /dev/hdg

 

to inspect the drive mode.

 

 

Ok, it turned out that the problem wasn't because i was using the higher speed cables the problem was that one of my new cables was flaky.  Luckily i bought extra ones (because of the bulk rate). When i switched to a different cable (still one of the round ones) it works fine now.

The point is not that round cables can't work - they often do, but that they are far more likely to cause the problems that you had.  Round cables and 36" cables are out-of-spec, and a departure from spec is generally a departure from the reliability guaranteed by the spec.  They may look good, add convenience and improve airflow, but 18" flat ribbon cables are what the spec calls for.  80 conductor flat cables were designed to reduce the crosstalk by guaranteeing a minimum signal separation between the signal-bearing lines, by taking the original 40 lines and inserting 39 grounded lines between them.  By mashing them together in a round cable, the guarantee is lost, and the cable may or may not be reliable at higher data transfer speeds.  Worse, it may appear to work fine most of the time, but be randomly unreliable.

 

If your unRAID server will be used for data critical to you, then 18" flat cables are best, and 24" only when necessary.  Longer or round cables would be best discarded, sold, or used for non-critical 'home' use.  (I'm in no way an electrical engineer, so I welcome corrections to the above.)

 

I'm happy that you have found a solution that seems to work fine for you, but I have to caution you that it would not be surprising if you have a very occasional disk error appear, while using your 36" round cables.

 

I'll be watching out for quirkyness very closely.  Eventually the unRAID box will likely be all SATA.  I'm starting it off with my old IDE drives while i copy data from my RAID5 array.  I have a lot of cables around.  I have a spot or two in my case though where 18 inch cables wouldn't work 24" might. 

 

I used to make my own SCSI cables back in the day i guess that would be the best way to do it now too. They always put the master and slave connectors so far apart :-/ If they made them closer together then i wouldnt have much issue with shorter cables.

...

SATA drives are typically two to three times faster than IDE drives.

...

 

Not true at all - The drives themselves are virutally identical, as is the sustained transfer rate seen on the cable.