<HTML>
<HEAD>
<TITLE>fragmentation question</TITLE>
</HEAD>
<BODY>
<FONT FACE="Calibri, Verdana, Helvetica, Arial"><SPAN STYLE='font-size:11pt'>Hello All,<BR>
I have an issue with fragmentation on a particular device<BR>
thanks for any advice.<BR>
<BR>
-Brady<BR>
<BR>
I have a Dell r510 with 12 disks <BR>
2xraid 5 (6 disks each) <BR>
raid group1:<BR>
48 GB carved out for os mounted as / <BR>
remaining space 2.7 TB for xfs mounted as /data1<BR>
raid group2:<BR>
48 GB for swap<BR>
remaining space 2.7 TB for xfs mounted as /data2<BR>
<BR>
The strange thing is that /data1 never gets fragmented where as /data2 is badly fragmented.<BR>
I believe increase allocsize would help, but not sure how to explain why /data2(/dev/sdd) always gets fragmented and not /data1(/dev/sdb)<BR>
<BR>
It's a data warehouse application. the I/O is balanced between /data1 and /data2:<BR>
output of xfs_db<BR>
[root@sdw4 data1]# xfs_db -c frag -r /dev/sdb<BR>
actual 14353, ideal 13702, fragmentation factor 4.54%<BR>
[root@sdw4 data1]# xfs_db -c frag -r /dev/sdd<BR>
actual 408674, ideal 13719, fragmentation factor 96.64%<BR>
df output<BR>
/dev/sdb 2.7T 967G 1.8T 36% /data1<BR>
/dev/sdd 2.7T 1.1T 1.7T 39% /data2<BR>
<BR>
LABEL=/data1 /data1 xfs allocsize=1048576,logbufs=8,noatime,nodiratime 0 0<BR>
LABEL=/data2 /data2 xfs allocsize=1048576,logbufs=8,noatime,nodiratime 0 0<BR>
<BR>
<BR>
raid config output:<BR>
[root@sdw4 data1]# omreport storage vdisk <BR>
List of Virtual Disks in the System<BR>
<BR>
Controller PERC H700 Integrated (Slot 4)<BR>
ID : 0<BR>
Status : Ok<BR>
Name : boot<BR>
State : Ready<BR>
Hot Spare Policy violated : Not Assigned<BR>
Virtual Disk Bad Blocks : No<BR>
Secured : Not Applicable<BR>
Progress : Not Applicable<BR>
Layout : RAID-5<BR>
Size : 48.99 GB (52602470400 bytes)<BR>
Device Name : /dev/sda<BR>
Bus Protocol : SAS<BR>
Media : HDD<BR>
Read Policy : No Read Ahead<BR>
Write Policy : Force Write Back<BR>
Cache Policy : Not Applicable<BR>
Stripe Element Size : 128 KB<BR>
Disk Cache Policy : Disabled<BR>
<BR>
ID : 1<BR>
Status : Ok<BR>
Name : data1<BR>
State : Ready<BR>
Hot Spare Policy violated : Not Assigned<BR>
Virtual Disk Bad Blocks : No<BR>
Secured : Not Applicable<BR>
Progress : Not Applicable<BR>
Layout : RAID-5<BR>
Size : 2,742.89 GB (2945150484480 bytes)<BR>
Device Name : /dev/sdb<BR>
Bus Protocol : SAS<BR>
Media : HDD<BR>
Read Policy : No Read Ahead<BR>
Write Policy : Force Write Back<BR>
Cache Policy : Not Applicable<BR>
Stripe Element Size : 128 KB<BR>
Disk Cache Policy : Disabled<BR>
<BR>
ID : 2<BR>
Status : Ok<BR>
Name : swap<BR>
State : Ready<BR>
Hot Spare Policy violated : Not Assigned<BR>
Virtual Disk Bad Blocks : No<BR>
Secured : Not Applicable<BR>
Progress : Not Applicable<BR>
Layout : RAID-5<BR>
Size : 48.99 GB (52602470400 bytes)<BR>
Device Name : /dev/sdc<BR>
Bus Protocol : SAS<BR>
Media : HDD<BR>
Read Policy : No Read Ahead<BR>
Write Policy : Force Write Back<BR>
Cache Policy : Not Applicable<BR>
Stripe Element Size : 128 KB<BR>
Disk Cache Policy : Disabled<BR>
<BR>
ID : 3<BR>
Status : Ok<BR>
Name : data2<BR>
State : Ready<BR>
Hot Spare Policy violated : Not Assigned<BR>
Virtual Disk Bad Blocks : No<BR>
Secured : Not Applicable<BR>
Progress : Not Applicable<BR>
Layout : RAID-5<BR>
Size : 2,742.89 GB (2945150484480 bytes)<BR>
Device Name : /dev/sdd<BR>
Bus Protocol : SAS<BR>
Media : HDD<BR>
Read Policy : No Read Ahead<BR>
Write Policy : Force Write Back<BR>
Cache Policy : Not Applicable<BR>
Stripe Element Size : 128 KB<BR>
Disk Cache Policy : Disabled<BR>
</SPAN></FONT>
</BODY>
</HTML>