I am just about to complete my media server by adding a parity drive. I will have 3 WD 1Tb drives , 2 fals drives and 1 eads drv. funny thing they are all 1TB drive but unraid is reportiung the total capacity of the eads drv as being about 1500 bytes larger than the fals drive currently installed. the parity drive (going in tonight and being burned in over the next few days) is another fals drv, if it has the same reported capacity as the otrher fals drv, will there be an effect on parity as they are in effect smaller than the other data drive (by 1500 bytes)

afaik the parity drive must be the same size or larger than all data drives for it to work.

 

I had this when I installed my system,  5 drives the same model and one was ~1500 bytes smaller.  It was plugged into SATA port 0 on the motherboard and I figure the motherboard is writing something to it. (Gigabyte mobo)  Only thing I could think might be happening.

I am just about to complete my media server by adding a parity drive. I will have 3 WD 1Tb drives , 2 fals drives and 1 eads drv. funny thing they are all 1TB drive but unraid is reportiung the total capacity of the eads drv as being about 1500 bytes larger than the fals drive currently installed. the parity drive (going in tonight and being burned in over the next few days) is another fals drv, if it has the same reported capacity as the otrher fals drv, will there be an effect on parity as they are in effect smaller than the other data drive (by 1500 bytes)

See this thread...

http://lime-technology.com/forum/index.php?topic=3865.0

 

The Gigabyte Motherboard BIOS is responsible in most cases so far, for adding the HPA to previously un-formatted drives, making them look smaller.

 

As already said, you will not be able to use the disk as the parity disk if it is smaller than any of the others... You will need to reset (remove) the HPA.  See the link in the other thread for one tool that may be used.

 

Joe L.

Solves my mystery then

 

Was most perturbed since 4 of the disks were in another system.... moved them across and they all turn out to be bigger.... 

This wiki page seems interesting...  You might be able to reset the HPA using the hdparm command included in unRAID

http://www.forensicswiki.org/wiki/DCO_and_HPA

 

Here is an example:

http://lkml.org/lkml/2009/1/3/59

 

Just be certain you know the drive you are operating on... Otherwise, it might really mess things up.   (Of course, that same advice would go for any drive you use any HPA utility on)

 

Also, DO NOT reset the HPA on a drive already assigned to the unRAID array.  The method used to determine if a drive is "Formatted" vs "Un-formatted" expects that a file-partition on a formatted drive uses all the available space on a drive.  If you reset the HPA to make it look a few meg bigger, the disk will show as "Un-formatted" because the partition does not use the newly accessible blocks, so it will be considered as "foreign" to unRAID.

 

Joe L.

The real worry seems to be a HPA getting written to the Parity drive, especially since it appears from the manual that there's no way to turn off this exciting little feature

Maybe we need Tom to add in hdparm -N /dev/sd? and capture via syslog (or devices screen in emhttp) for diagnostics.

 

I never knew this option was there.

 

hdparm -N /dev/sda

 

Disabled HPA:

 

/dev/sda:

max sectors   = 1465149168/1465149168, HPA is disabled

 

Enabled HPA:

 

/dev/sdc:

max sectors   = 586070255/586072368, HPA is enabled

A little more searching seems to suggest the bios might have some hidden options you can access by hitting CTRL-F1 on the main page.

 

I'll check when I get home to see if this lets you turn off bios protection.

I am just about to complete my media server by adding a parity drive. I will have 3 WD 1Tb drives , 2 fals drives and 1 eads drv. funny thing they are all 1TB drive but unraid is reportiung the total capacity of the eads drv as being about 1500 bytes larger than the fals drive currently installed. the parity drive (going in tonight and being burned in over the next few days) is another fals drv, if it has the same reported capacity as the otrher fals drv, will there be an effect on parity as they are in effect smaller than the other data drive (by 1500 bytes)

See this thread...

http://lime-technology.com/forum/index.php?topic=3865.0

 

The Gigabyte Motherboard BIOS is responsible in most cases so far, for adding the HPA to previously un-formatted drives, making them look smaller.

 

As already said, you will not be able to use the disk as the parity disk if it is smaller than any of the others... You will need to reset (remove) the HPA.  See the link in the other thread for one tool that may be used.

 

Joe L.

 

Thanks for the information, a quck search on some of the links off of the link you gave me yileded this :

http://lime-technology.com/forum/index.php?topic=3894.msg34327#msg34327

 

I have a gigabyte m/b , so this was quite a surprise to me. I think I have put the 1st data drive in one of the 1st sata ports, (the fals drive is the one) so my assumption is the hpa is on that drive, so I should still be ok. i will as the post suggests put my parity drive on the last sata port however.

Maybe we need Tom to add in hdparm -N /dev/sd? and capture via syslog (or devices screen in emhttp) for diagnostics.

Not a bad idea

I never knew this option was there.

Neither did I until about 20 minutes ago.  But don't feel bad, I've spent the last 20 minutes trying to find an on-line "man" page that shows the

"-N" option and describes its use...

 

So far, none of the on-line pages I've looked at show it.   Could be why it is not very well known.... (Except to "experts"*)

 

Joe L.

* Usually, an "expert" is somebody who has read the "man" page, but in this case... until I find a man page that mentions it, I'm not an "expert"

OK, now I'm an "expert"

 

The manual page that mentions the -N option is here:

https://www.cs.drexel.edu/cgi-bin/manServer.pl/usr/share/man/man8/hdparm.8

 

The section of the page we are interested in is:

-N Get/set max visible number of sectors, also known as the Host Protected Area setting.

Without a parameter, -N displays the current setting, which is reported as two values:

    the first gives the current max sectors setting, and the second shows the native (real) hardware limit for the disk.

The difference between these two values indicates how many sectors of the disk are currently hidden from the operating system, in the form of a Host Protected Area (HPA). This area is often used by computer makers to hold diagnostic software, and/or a copy of the originally provided operating system for recovery purposes.

 

To change the current max (VERY DANGEROUS, DATA LOSS IS EXTREMELY LIKELY), a new value should be provided (in base10) immediately following the -N flag. This value is specified as a count of sectors, rather than the "max sector address" of the drive. Drives have the concept of a temporary (volatile) setting which is lost on the next hardware reset, as well as a more permanent (non-volatile) value which survives resets and power cycles. By default, -N affects only the temporary (volatile) setting. To change the permanent (non-volatile) value, prepend a leading p character immediately before the first digit of the value.

 

Drives are supposed to allow only a single permanent change per session. A hardware reset (or power cycle) is required before another permanent -N operation can succeed. Note that any attempt to set this value may fail if the disk is being accessed by other software at the same time. This is because setting the value requires a pair of back-to-back drive commands, but there is no way to prevent some other command from being inserted between them by the kernel. So if it fails initially, just try again.

 

So it appears as if we can first use hdparm -N /dev/sdX to get the full size, then use hdparm -N pNNNNNNNNNN to set the new limit.   You can only set the HPA size once per power cycle.  (And don't forget the leading "p" on the size to make it permanent.)

 

Joe L.

i also see in another thread that hpa does not occurr on drives mounted to onboard cards. I am not worried about having hpa appear on my data drives but am on the parity . I have an old promise t x2 sata card , it is a generation 1 card with sata speeds @1.5 MB/s , will that work?

i also see in another thread that hpa does not occurr on drives mounted to onboard cards. I am not worried about having hpa appear on my data drives but am on the parity . I have an old promise t x2 sata card , it is a generation 1 card with sata speeds @1.5 MB/s , will that work?

It will, but it may slow down the overall "write" speed to the array.  Odds are it will not, as the rotational speed of the drive is the biggest factor.

 

From my reading, the BIOS puts the HPA on the first drive on the controller... You might be fine with it on a higher numbered port on the MB

 

Of course, if you have  an option in the BIOS to disable the "Bios-Protection" feature, that's even better. 

 

You'll know for sure when you go to try to assign it as the parity drive.  If it complains it is too small, then try the two hdparm commands (one to get the size, the other to set it) 

 

I'm not sure when the management "Devices" page gets the sizes of the drives, so it might be tricky.  You might need to kill it and re-start it.

Stop the array, then type

killall emhttp

then re-invoke it

/usr/local/sbin/emhttp &

i also see in another thread that hpa does not occurr on drives mounted to onboard cards. I am not worried about having hpa appear on my data drives but am on the parity . I have an old promise t x2 sata card , it is a generation 1 card with sata speeds @1.5 MB/s , will that work?

 

It may work, but parity should be on your largest and fastest drive.

For writes it will be the most used drive in the system.

Every write operating to a parity protected drive requires a read from the parity and then a re-write to parity.

ok will revistit this once I have drive in place. UPS deliveres today , will burn in and I hope to put it into the array sometime later this week. (tomorrow if I dont get any errors cropping up from the preclear)

 

will try to add to the highest sata port i have

ok will revistit this once I have drive in place. UPS deliveres today , will burn in and I hope to put it into the array sometime later this week. (tomorrow if I dont get any errors cropping up from the preclear)

 

will try to add to the highest sata port i have

If it was to be used as a data drive I'd say run the hdparm -N command on the drive BEFORE you pre-clear it..., otherwise the partition it sets up would be based on the HPA. 

 

Since it is for the parity drive, it really does not matter, other than the last few meg of the drive will not be tested/exercised if an HPA is present.

 

I really think you should disable the bios feature if Control-F1 gets you to the options for it.  It will make your life so much easier going forward.

 

Joe L.

I checked my BIOS and couldn't find a way of disabling saving to the HPA even after revealing the hidden options with CTRL-F1.  Motherboard is a Gigabyte MA74GN-S2H.

 

 

I checked my BIOS and couldn't find a way of disabling saving to the HPA even after revealing the hidden options with CTRL-F1.  Motherboard is a Gigabyte MA74GN-S2H.

 

 

I have exactly the same board.

ok I have just put the arrya on line and wouldt you know it the 2 fals drives have the same value 976,761,496 while the eads drv has 976,762,552  about 1000 bytes different I put the second fals drive on one of the last sata ports too . so now I am copying data over to the fals drv, I am going to use the eads drv as my parity and put it on a pci promise sata 2 card , it is only a 1.5 Mb/s is there any down side as my intended use is as a movie server , and small stuff form the 3 pcs it will serve?