Is Write back cache enabled on physical disks of Perc 6/i ?

Dushyanth dushyanth at gmail.com
Wed Mar 25 11:40:23 CDT 2009


Hi guys,

I having a bunch of mail servers suffering ext3 FS corruption which might be due
to write back cache enabled on the physical disks. (Refer to
http://article.gmane.org/gmane.comp.file-systems.ext3.user/4296 for the
corruption details)

Iam not able to verify whether the physical disks on a perc 6/i has write back
cache enabled as OMSA physical disk properties does not show this property

Controller PERC 6/i Integrated (Embedded)
ID                        : 0:0:0
Status                    : Ok
Name                      : Physical Disk 0:0:0
State                     : Online
Failure Predicted         : No
Progress                  : Not Applicable
Type                      : SATA
Capacity                  : 465.25 GB (499558383616 bytes)
Used RAID Disk Space      : 465.25 GB (499558383616 bytes)
Available RAID Disk Space : 0.00 GB (0 bytes)
Hot Spare                 : No
Vendor ID                 : DELL
Product ID                : ST3500630AS
Revision                  : 3.AAK
Serial No.                : 6QG1B1T7    6QG1B1T7
Negotiated Speed          : Not Available
Capable Speed             : Not Available
Manufacture Day           : Not Available
Manufacture Week          : Not Available
Manufacture Year          : Not Available
SAS Address               : 1221000000000000

These servers are all Dell and have Battery backup.

# omreport chassis batteries
Batteries

Health : Ok

Individual Battery Elements
Index      : 0
Status     : Ok
Probe Name : System Board CMOS Battery
Reading    : Good

Also, If a IPMI based power recycle is executed on a busy mail server and
assuming write back cache is enabled on the physical disks and also on the
virtual disk - would the controller ensure data is flushed by the physical disks
cache as well ? Cos if the controller doesn't ensure that physical disks flush
their cache it might lead to FS corruption.

Any pointers/suggestions would be of great help.

TIA
Dushyanth



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