[OmniOS-discuss] Slow zfs writes

[Eric Sproul]

On Mon, Feb 11, 2013 at 7:48 AM, Ram Chander <ramquick at gmail.com> wrote:
> Hi,
>
> My OI box is expreiencing slow zfs writes ( around 30 times slower ). iostat
> reports below error though pool is healthy. This is happening in past 4 days
> though no change was done to system. Is the hard disks faulty ?
> Please help.

How have you measured this 30x drop in performance?  You haven't
provided any data.


> c4t0d0           Soft Errors: 0 Hard Errors: 5 Transport Errors: 0
> Vendor: iDRAC    Product: Virtual CD       Revision: 0323 Serial No:
> Size: 0.00GB <0 bytes>
> Media Error: 0 Device Not Ready: 5 No Device: 0 Recoverable: 0
> Illegal Request: 1 Predictive Failure Analysis: 0

I wouldn't worry about errors here.  This is a virtual device provided
by your server's lights-out management system.


> root at host:~# fmadm faulty
> --------------- ------------------------------------  --------------
> ---------
> TIME            EVENT-ID                              MSG-ID
> SEVERITY
> --------------- ------------------------------------  --------------
> ---------
> Jan 05 08:21:09 7af1ab3c-83c2-602d-d4b9-f9040db6944a  ZFS-8000-HC    Major
>
> Host        : host
> Platform    : PowerEdge-R810
> Product_sn  :
>
> Fault class : fault.fs.zfs.io_failure_wait
> Affects     : zfs://pool=test
>                   faulted but still in service
> Problem in  : zfs://pool=test
>                   faulted but still in service
>
> Description : The ZFS pool has experienced currently unrecoverable I/O
>                     failures.  Refer to http://illumos.org/msg/ZFS-8000-HC
> for
>               more information.
>
> Response    : No automated response will be taken.
>
> Impact      : Read and write I/Os cannot be serviced.
>
> Action      : Make sure the affected devices are connected, then run
>                     'zpool clear'.

What has happened since January 5?  The pool appears fine now.  Did
you run a scrub?  Replace devices?  Reboot?  It looks like ZFS
encountered an underlying problem with the hardware.

Eric