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Good morning all.
This is my first question on the forum, so be gentle with me
I don't have a support problem to solve, I'm just using symstat to gather some info & then trying to make sure I understand the results.
What I have is a DMX-3 1500 & the volume I'm looking at is a a 5GB volume (0278) which is a Windows 2K3 boot lun.
This server has just been deployed so the Windows guys are no doubt copying zip files around & installing software etc so I thought I'd run symstat to see how it looked. I've pasted the symstat output at the end of this post.
Now here's the bit where I need you guys to check my logic if you don't mind ?
The highest number of write pending tracks in the output is at 10:14:58 where it hits 2036 in the WP column.
Given that it's a DMX-3 the track size is 64KB I think that at 10:14:58 this device had
130304KB WP data in cache which I calculated like this :-
2036 x 64 = 130304KB
Or around 127.25MB
130304 / 1024 = 127.25MB
I also have in the back of my mind that I've read that a volume in the DMX has 4% of its size assigned in cache for WP which if correct means that my 5GB volume has around 200MB ringfenced in cache, after which writes may be held while data is flushed to disk.
It would be great if someone had a second to sense check my logic here & give me any insight as to whether I'm on target with my reasoning ?
# symstat -dev 0278 -i 5
DEVICE IO/sec KB/sec % Hits %Seq Num WP
10:14:05 READ WRITE READ WRITE RD WRT READ Tracks
10:14:10 0278 (Not Visible ) 72 184 845 1367 75 100 0 732
10:14:16 0278 (Not Visible ) 31 224 328 2120 81 100 0 1020
10:14:21 0278 (Not Visible ) 14 74 275 728 50 100 0 1136
10:14:26 0278 (Not Visible ) 28 86 493 673 68 100 0 1190
10:14:32 0278 (Not Visible ) 1 23 16 271 0 100 0 1188
10:14:37 0278 (Not Visible ) 1 11 23 89 0 100 0 1096
10:14:42 0278 (Not Visible ) 22 310 346 1827 73 100 0 1084
10:14:48 0278 (Not Visible ) 4 72 127 2685 100 100 0 1408
10:14:53 0278 (Not Visible ) 30 148 510 3100 63 100 0 1814
10:14:58 0278 (Not Visible ) 78 139 584 1885 78 100 0 2036
10:15:04 0278 (Not Visible ) 7 30 112 318 57 100 0 1964
10:15:09 0278 (Not Visible ) 3 73 57 460 33 100 0 1728
10:15:15 0278 (Not Visible ) 54 35 1374 320 31 100 2 1268
10:15:20 0278 (Not Visible ) 0 12 0 76 N/A 100 N/A 1248
Thanks
Ben
This is my first question on the forum, so be gentle with me
I don't have a support problem to solve, I'm just using symstat to gather some info & then trying to make sure I understand the results.
What I have is a DMX-3 1500 & the volume I'm looking at is a a 5GB volume (0278) which is a Windows 2K3 boot lun.
This server has just been deployed so the Windows guys are no doubt copying zip files around & installing software etc so I thought I'd run symstat to see how it looked. I've pasted the symstat output at the end of this post.
Now here's the bit where I need you guys to check my logic if you don't mind ?
The highest number of write pending tracks in the output is at 10:14:58 where it hits 2036 in the WP column.
Given that it's a DMX-3 the track size is 64KB I think that at 10:14:58 this device had
130304KB WP data in cache which I calculated like this :-
2036 x 64 = 130304KB
Or around 127.25MB
130304 / 1024 = 127.25MB
I also have in the back of my mind that I've read that a volume in the DMX has 4% of its size assigned in cache for WP which if correct means that my 5GB volume has around 200MB ringfenced in cache, after which writes may be held while data is flushed to disk.
It would be great if someone had a second to sense check my logic here & give me any insight as to whether I'm on target with my reasoning ?
# symstat -dev 0278 -i 5
DEVICE IO/sec KB/sec % Hits %Seq Num WP
10:14:05 READ WRITE READ WRITE RD WRT READ Tracks
10:14:10 0278 (Not Visible ) 72 184 845 1367 75 100 0 732
10:14:16 0278 (Not Visible ) 31 224 328 2120 81 100 0 1020
10:14:21 0278 (Not Visible ) 14 74 275 728 50 100 0 1136
10:14:26 0278 (Not Visible ) 28 86 493 673 68 100 0 1190
10:14:32 0278 (Not Visible ) 1 23 16 271 0 100 0 1188
10:14:37 0278 (Not Visible ) 1 11 23 89 0 100 0 1096
10:14:42 0278 (Not Visible ) 22 310 346 1827 73 100 0 1084
10:14:48 0278 (Not Visible ) 4 72 127 2685 100 100 0 1408
10:14:53 0278 (Not Visible ) 30 148 510 3100 63 100 0 1814
10:14:58 0278 (Not Visible ) 78 139 584 1885 78 100 0 2036
10:15:04 0278 (Not Visible ) 7 30 112 318 57 100 0 1964
10:15:09 0278 (Not Visible ) 3 73 57 460 33 100 0 1728
10:15:15 0278 (Not Visible ) 54 35 1374 320 31 100 2 1268
10:15:20 0278 (Not Visible ) 0 12 0 76 N/A 100 N/A 1248
Thanks
Ben
