W dniu 2/11/2011 8:20 PM, Rodolfo Gouveia pisze:
On Thu, Feb 10, 2011 at 09:49:43PM -0500, Nick Holland wrote:
Also, check to see if your RAID card has a battery for its cache, if it
doesn't, a lot of RAID controllers drop to non-cached writes, and often
seem to slow down way beyond what you'd expect just to make you buy the
dang battery :). I believe most of the current crop of Dell RAID
controllers have an option buried in the RAID setup screens to cache
writes even without a battery. Don't blame me (or Dell, or anyone else)
if you trip over the power cord and blow away your array.
I second this too. Check if you have that write cache enabled.
Hi
Machine Bios, DRAC and RAID firmware are fully updated.
There is no option in RAID firmware to enable write cache.
According to this:
http://www.dell.com/content/topics/topic.aspx/global/products/pvaul/topics/en/us/raid_controller?c=us&dgc=CJ&cid=24471&lid=566643&acd=10550055-4166869-1hyp1szsf4our
and this:
http://support.dell.com/support/edocs/storage/storlink/h200/en/ug/html/features.htm#wp1062398
Controller doesn't have internal cache and
"On a PERC H200 card, caching is forced to be disabled for all physical
disks configured into a virtual disk, regardless of the drive type and
default drive settings."
I guess that Linux somehow reenables disc drive cache.
I've tried to do that with OpenBSD by writing WCE:1<enter> to this command:
scsi -f /dev/rsd0c -m 8 -e
But it fails.
Does anyone know how to reenable disks cache?
# scsi -f /dev/rsd0c -m 8 -e
SCIOCCOMMAND ioctl: Command accepted.
return status 3 (Sense Returned) host adapter status 2
Command out (6 of 6):
15 00 00 00 18 00
Data out (0 of 24):
Error code is "current errors"
Segment number is 07
Sense key is "Illegal request"
The Information field is not valid but contains ffffffffff000002
(-16777214).
The Command Specific Information field is 05000380 (83886976).
Additional sense code: 20
Additional sense code qualifier: 00
Illegal value in the parameter list.
Byte 0 (value 00) is illegal.
sense (18 of 48):
70 07 05 ff 00 00 02 00 05 00 03 80 20 00 04 80
00 00
# scsi -f /dev/rsd0c -m 8
IC: 0
ABPF: 0
CAP: 0
DISC: 0
SIZE: 0
WCE: 0
MF: 0
RCD: 0
Demand Retention Priority: 0
Write Retention Priority: 0
Disable Pre-fetch Transfer Length: 65535
Minimum Pre-fetch: 0
Maximum Pre-fetch: 65280
Maximum Pre-fetch Ceiling: 65535
FSW: 0
LBCSS: 0
DRA: 0
Vendor-specific: 0
NV_DIS: 0
Number of Cache Segments: 15
Cache Segment Size: 0
Lukasz
