Poor performace in OpenSolaris with 4K sector drive (WD10EARS) in ZFS RAIDZ


#1

Folks,

I tried to add this drive to an actual 3 disks RAIDZ already composed of a WD10EACS-00ZJB0 and a WD10EADS-65L5B1. The performance was horrible.
You can check a similar iostat output showing the long wait times in:

http://pastie.org/889572

While the other 512-byte sector HDDs were reading/writing at 30MB/s sustained, this EARS model did not exceeded the 1MB/s barrier.

I know for sure that this is related to the 512-byte sector firmware emulation, because the disk works perfectly well if I partition it in a 4k-sector alignment.

The thing is that even in that way, using it in a ZFS RAIDZ configuration the performance is very poor because RAIDZ uses a dynamic stripe size.

The bottom line here is that folks like me, that use different versions of Unix, need the firmware to present the disk as a 4K-sector disk to unleash the full potential of the technology. The OS is already prepared to support that sector size, no need for emulation here.

Could you please release a firmware version with no emulation whatsoever? Just the real thing.

Thanks in advance.

Leandro Vanden Bosch.


#2

In favor of the WD10EARS I should also add that the disk works perfectly fine if you use it in a non-RAIDZ configuration (like stand-alone or mirrored).

This is the output I just captured while uncompressing a rar file:

extended device statistics              
    r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
  161.3 0.0 20544.0 0.0 0.0 1.8 0.0 11.0 0 22 c12t3d0
  236.7 0.0 30144.0 0.0 0.0 2.8 0.0 11.9 0 32 c12t3d0
  252.3 0.0 32298.7 0.0 0.0 2.8 0.0 11.0 0 30 c12t3d0
   19.3 500.7 2474.7 63636.2 0.0 6.8 0.0 13.1 1 69 c12t3d0
  194.3 196.7 24874.1 23369.0 2.3 2.6 5.9 6.5 48 46 c12t3d0
  234.3 0.0 29994.6 0.0 2.6 0.3 11.2 1.4 32 32 c12t3d0
   70.7 510.3 9045.4 64833.0 6.6 0.7 11.4 1.3 75 74 c12t3d0
   99.7 186.7 12757.6 22173.7 3.6 0.3 12.7 1.2 48 35 c12t3d0
  235.3 0.0 30058.5 0.0 2.3 0.3 10.0 1.2 27 28 c12t3d0
   12.3 340.7 1536.0 43278.5 3.9 0.4 11.0 1.3 44 44 c12t3d0

This is how ZFS automatically partitions the disk when you use it as a whole:

$ pfexec prtvtoc /dev/rdsk/c12t3d0s2
* /dev/rdsk/c12t3d0s2 partition map
*
* Dimensions:
* 512 bytes/sector
* 1953525168 sectors
* 1953525101 accessible sectors
*
* Flags:
* 1: unmountable
* 10: read-only
*
* Unallocated space:
* First Sector Last
* Sector Count Sector
* 34 222 255
*
* First Sector Last
* Partition Tag Flags Sector Count Sector Mount Directory
       0 4 00 256 1953508495 1953508750
       8 11 00 1953508751 16384 1953525134

Looking perfectly aligned.

Leandro.


#3

hot_flyback wrote:

In favor of the WD10EARS I should also add that the disk works perfectly fine if you use it in a non-RAIDZ configuration (like stand-alone or mirrored).

This is the output I just captured while uncompressing a rar file:

extended device statistics
r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device
161.3 0.0 20544.0 0.0 0.0 1.8 0.0 11.0 0 22 c12t3d0
236.7 0.0 30144.0 0.0 0.0 2.8 0.0 11.9 0 32 c12t3d0
252.3 0.0 32298.7 0.0 0.0 2.8 0.0 11.0 0 30 c12t3d0
19.3 500.7 2474.7 63636.2 0.0 6.8 0.0 13.1 1 69 c12t3d0
194.3 196.7 24874.1 23369.0 2.3 2.6 5.9 6.5 48 46 c12t3d0
234.3 0.0 29994.6 0.0 2.6 0.3 11.2 1.4 32 32 c12t3d0
70.7 510.3 9045.4 64833.0 6.6 0.7 11.4 1.3 75 74 c12t3d0
99.7 186.7 12757.6 22173.7 3.6 0.3 12.7 1.2 48 35 c12t3d0
235.3 0.0 30058.5 0.0 2.3 0.3 10.0 1.2 27 28 c12t3d0
12.3 340.7 1536.0 43278.5 3.9 0.4 11.0 1.3 44 44 c12t3d0

 

This is how ZFS automatically partitions the disk when you use it as a whole:

$ pfexec prtvtoc /dev/rdsk/c12t3d0s2
* /dev/rdsk/c12t3d0s2 partition map

  • Dimensions:
  • 512 bytes/sector
  • 1953525168 sectors
  • 1953525101 accessible sectors

  • Flags:

  • 1: unmountable
  • 10: read-only

  • Unallocated space:

  • First Sector Last
  • Sector Count Sector
  • 34 222 255

  • First Sector Last

  • Partition Tag Flags Sector Count Sector Mount Directory
    0 4 00 256 1953508495 1953508750
    8 11 00 1953508751 16384 1953525134

 

Looking perfectly aligned.

Leandro.

 

That's because the drive is not designed for use in a RAID configuration, and will drop out sooner or later.


#4

Bill,

Thanks for your reply.

I know EARS was not designed specifically for RAID but neither EACS or EADS and are working perfectly fine in my RAIDZ for over a year now.

The thing is that the RE3 and RE4 models are not available to my local market and I also I wouldn't buy those just for an storage home server.

What I and many other *nix users out there would want is a firmware release that directly exposes the 4K sectors without any 512-byte emulation in the middle. We don't want a future model with that feature, we want the actual disks that we have to function like they should.

Let's put it like this, if WD is taking in consideration the great majority of persons that use Windows XP and would need to set the jumper on the disk to re-align the I/O, why wouldn't the *nix users have their non-emulated firmware update?

Some people could be happy "jumpering" their drives and some other flashing them.

Besides, I believe a senior engineer/developer won't take more than an hour to comment all the unneeded lines in the code and compile a new firmware.

Thanks,

Leandro.


#5

This sounds like an idea for our Ideas Lab.  Eventually, everything will be non-emulated 4K anyway.  So, maybe you can help get it rolling by suggesting it.

Ideas Lab
http://community.wdc.com/t5/community/categorypage/category-id/idea


#6

Sounds good. Thanks for the suggestion.

Regards,

Leandro.


#7

Posted:

http://community.wdc.com/t5/WD-TV-Live-Ideas/Release-non-512-byte-sector-emulated-firmware-for-WD-EARS/idi-p/21347

Leandro.