[Bug 13499] New: Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[Bug 13499] New: Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=13499

           Summary: Write cache: disabled, read cache: enabled, supports
                    DPO and FUA? it's  bug???
           Product: SCSI Drivers
           Version: 2.5
    Kernel Version: 2.6.22 - 2.6.30
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
        AssignedTo: scsi_drivers-other@kernel-bugs.osdl.org
        ReportedBy: lxy9805287@163.com
        Regression: No


scsi0 : LSI Logic SAS based MegaRAID driver
scsi 0:0:0:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
done.
Begin: Running /scripts/init-premount ... scsi 0:0:1:0: Direct-Access    
SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:2:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:3:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:4:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:5:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:6:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:7:0: Direct-Access     SEAGATE  ST9146852SS      HT03 PQ: 0 ANSI: 5
scsi 0:0:32:0: Enclosure         DP       BACKPLANE        1.07 PQ: 0 ANSI: 5
scsi 0:2:0:0: Direct-Access     DELL     PERC 6/i         1.21 PQ: 0 ANSI: 5
scsi 0:0:32:0: Attached scsi generic sg0 type 13
sd 0:2:0:0: [sda] 1998323712 512-byte hardware sectors (1023142 MB)
sd 0:2:0:0: [sda] Write Protect is off
sd 0:2:0:0: [sda] Write cache: disabled, read cache: enabled, supports DPO and
FUA
sd 0:2:0:0: [sda] 1998323712 512-byte hardware sectors (1023142 MB)
sd 0:2:0:0: [sda] Write Protect is off
sd 0:2:0:0: [sda] Write cache: disabled, read cache: enabled, supports DPO and
FUA
 sda: sda1 sda4 < sda5 sda6 sda7 sda8 sda9 >

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[Bug 13499] Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=13499





--- Comment #1 from ping.li <lxy9805287@163.com>  2009-06-10 14:00:53 ---
Write cache: disabled, read cache: enabled,


why Write cache: disabled??

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Re: [Bug 13499] Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[James Bottomley]

On Wed, 2009-06-10 at 14:00 +0000, bugzilla-daemon@bugzilla.kernel.org
wrote:
> why Write cache: disabled??

The SCSI mid layer is merely reporting what your array is telling it.
For arrays without a battery backed cache, write through configuration
(i.e. read cache enabled, write cache disabled) is the usual safe
default.

You can alter your write cache settings using Doug Gilbert's
sg3-utils ... but be warned, enabling the write cache without battery
backing in an array is a dangerous thing to do since most arrays have
huge caches, they either ignore SYNCHRONIZE CACHE (which would leave you
vulnerable to data loss on power failure) or take such a long time, it
would kill performance.

James

[Bug 13499] Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=13499





--- Comment #2 from Anonymous Emailer <anonymous@kernel-bugs.osdl.org>  2009-06-10 14:14:13 ---
Reply-To: James.Bottomley@HansenPartnership.com

On Wed, 2009-06-10 at 14:00 +0000, bugzilla-daemon@bugzilla.kernel.org
wrote:
> why Write cache: disabled??

The SCSI mid layer is merely reporting what your array is telling it.
For arrays without a battery backed cache, write through configuration
(i.e. read cache enabled, write cache disabled) is the usual safe
default.

You can alter your write cache settings using Doug Gilbert's
sg3-utils ... but be warned, enabling the write cache without battery
backing in an array is a dangerous thing to do since most arrays have
huge caches, they either ignore SYNCHRONIZE CACHE (which would leave you
vulnerable to data loss on power failure) or take such a long time, it
would kill performance.

James

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[Bug 13499] Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=13499





--- Comment #3 from ping.li <lxy9805287@163.com>  2009-06-10 17:04:29 ---
1. BBU  status is ok
./MegaCli64 -AdpBbuCmd -GetBbuStatus -a0

BBU status for Adapter: 0

BatteryType: BBU
Voltage: 4058 mV
Current: 0 mA
Temperature: 19 C
Firmware Status: 00000000

Battery state:

GasGuageStatus:
  Fully Discharged        : No
  Fully Charged           : Yes
  Discharging             : Yes
  Initialized             : Yes
  Remaining Time Alarm    : No
  Remaining Capacity Alarm: No
  Discharge Terminated    : No
  Over Temperature        : No
  Charging Terminated     : Yes
  Over Charged            : No

Relative State of Charge: 98 %
Charger Status: Complete
Remaining Capacity: 1634 mAh
Full Charge Capacity: 1662 mAh
isSOHGood: Yes

2. Cache Policy is default,and try change setting but problem still.

./MegaCli64 -LDinfo -L0 -a0
Adapter 0 -- Virtual Drive Information:
Virtual Disk: 0 (target id: 0)
Name:
RAID Level: Primary-5, Secondary-0, RAID Level Qualifier-3
Size:975744MB
State: Optimal
Stripe Size: 64kB
Number Of Drives:8
Span Depth:1
Default Cache Policy: WriteBack, ReadAheadNone, Direct, Write Cache OK if Bad
BBU
Current Cache Policy: WriteBack, ReadAheadNone, Direct, Write Cache OK if Bad
BBU
Access Policy: Read/Write
Disk Cache Policy: Enabled

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[Bug 13499] Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=13499


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |alan@lxorguk.ukuu.org.uk
         Resolution|                            |OBSOLETE




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[Bug 13499] Write cache: disabled, read cache: enabled, supports DPO and FUA? it's bug???

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=13499


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED




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