I have IBM SAN STORAGE DS4100 and one of the cache battery for the controller is dead. Suddenly the performance has been degraded and access to SAN disks ( reading and writing ) became very slow ?
My query: Replacing the battery will take 6 days, so in the mean time what are the ways to speed up the access to the disks ?
1) Could I move the Array from the failed battery controller B to controller A ? Does it need to have multipath MPIO installed and configured ?
2) disable the write cache and enable write-cache working without battery ==> Will it improve the performance ?
3) powering off SAN Storage completely and restarting it ? ==> will there be any implications ?
Code:
SUMMARY------------------------------
Number of controllers: 2
Number of arrays: 3
Total number of logical drives (includes an access logical drive): 5 of 1024 used
Number of standard logical drives: 4
Number of access logical drives: 1
Number of drives: 11
Supported drive types: Fibre (11)
Total hot spare drives: 0
Standby: 0
In use: 0
Access logical drive: LUN 31 (see Mappings section for details)
Default host type: AIX (Host type index 6)
Current configuration
Firmware version: 06.12.16.00
NVSRAM version: N1722F600R912V05
Pending configuration
Staged firmware download supported?: Yes
Firmware version: None
NVSRAM version: None
Transferred on: None
NVSRAM configured for batteries?: Yes
Start cache flushing at (in percentage): 80
Stop cache flushing at (in percentage): 80
Cache block size (in KB): 4
Media scan frequency (in days): 30
Failover alert delay (in minutes): 5
Feature enable identifier: 3034383037003834333831004133365E
Storage Subsystem worldwide name (ID): 600A0B800016E56E000000004133366F
ENCLOSURES------------------------------
Drive/Controller Enclosure 0 Overall Component Information
Drive technology: Fibre channel
Minihub data rate mismatch: No
Part number: PN 24P8129
Serial number: SN 13G6078
Vendor: VN IBM
Date of manufacture: August 1, 2004
Enclosure path redundancy: OK
Fan canister
Location: Left
Status: Optimal
Fan canister
Location: Right
Status: OptimalBattery status: Optimal
Location: Controller in slot A
Age: 858 day(s)
Days until replacement: 311 day(s)
Battery status: Removed
Location: Controller in slot B
Age: 1055 day(s)
Days until replacement: 114 day(s)
.....
.....
.....
DETAILS
Logical Drive name: oraappvg
Logical Drive ID: 60:0a:0b:80:00:16:e5:6e:00:00:13:1a:41:87:1f:12
Subsystem ID (SSID): 0
Status: Optimal
Drive type: Fibre Channel
Enclosure loss protection: No
Preferred owner: Controller in slot A
Current owner: Controller in slot A
Capacity: 135.732 GB
RAID level: 5
Segment size: 64 KB
Modification priority: High
Associated array: 1Read cache: Enabled
Write cache: Enabled (currently suspended)
Write cache without batteries: Disabled
Write cache with mirroring: Enabled (currently suspended)
Flush write cache after (in seconds): 10.00
Cache read ahead multiplier: 1
Enable background media scan: Enabled
Media scan with redundancy check: Disabled
http://www.tek-tips.com/viewthread.cfm?qid=1493007&page=41
From the storage manager you have to findout the arrays which are pointing to that suspected controller ( say Controller-B) against which the battery is failed.
Now you have to move the arrays from controller-B to Controller-A and make sure while doing this there is no I/O with the disks in the stroage.
It takes little bit of time to move the arrays from the contr-B to contr-A. After this, you have to disable the controller through storage manager. After doing this you can take that module out from DS4300 and replace the battery.
After change the battery, you please put it back into storage DS4300 unit and enable the controller.
After enable the controller, you have to move all the arrays back which you previoulsy moved from Contr.-B to Contr.-A
The Storage Manager Help is pretty staright forward in which you can see the step by step process to change the battery.
---------- Post updated at 01:43 PM ---------- Previous update was at 11:47 AM ----------
I think Multipath is not enabled on the system even though HACMP is installed
# lsdev -Cc disk
hdisk0 Available 1S-08-00-8,0 16 Bit LVD SCSI Disk Drive
hdisk1 Available 1S-08-00-9,0 16 Bit LVD SCSI Disk Drive
hdisk2 Available 1V-08-02 1722-600 (600) Disk Array Device
hdisk3 Available 1D-08-02 1722-600 (600) Disk Array Device
hdisk4 Available 1V-08-02 1722-600 (600) Disk Array Device
hdisk5 Available 1D-08-02 1722-600 (600) Disk Array Device
# lspv
hdisk1 0059da1d0ddcf5b9 rootvg active
hdisk2 0059da1d0d864640 oraappvg active
hdisk3 0059c87d0d80db98 oradbvg
hdisk4 0059c87d7662aa73 None
hdisk0 0059da1d968b4e5f rootvg active
hdisk5 0059c87d27ac212f oradbvg
# lspath
Enabled hdisk0 scsi0
Enabled hdisk1 scsi0
Last edited by filosophizer; 05-01-2011 at 05:20 PM..
The problem was solved by disabling the read and write cache for the disks under the controller which had the failed battery.
I think it could have been solved also by moving the disks from Controller B to controller A , but this I am not sure if you don't have MPIO ( Multi path I/O ) how will it behave ?
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