<html><head><style type="text/css"><!-- DIV {margin:0px} --></style></head><body><div style="font-family:garamond, new york, times, serif;font-size:12pt"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;"><div>Examine the drives with smartctl:<br><br># smartctl -a /dev/hda<br><br>or, if you're using SATA drives<br><br># smartctl -d ata -a /dev/sda <br><br>If you're getting warning messages, take out that drive.<br><br><span><a target="_blank" href="http://smartmontools.sourceforge.net/">http://smartmontools.sourceforge.net/</a></span><br><br>John<br><br>----- Original Message ----<br>From: Daniel Walton <dwalton@cisco.com><br>To: Discussion about mythtv <mythtv-users@mythtv.org><br>Sent: Tuesday, March 21, 2006 2:07:22 PM<br>Subject: Re: [mythtv-users] 'wa' field in 'top' is +90% when recording a show<br><br><div>On Mon, 20 Mar 2006, Brian Wood wrote:<br><br>><br>> On Mar 20, 2006, at 11:25 AM, Daniel Walton
wrote:<br>><br>> > I've noticed that sometimes when I'm recording tv and when watching certain<br>> > shows I've recorded, the cpu is pegged at 99% or 100% with most of the<br>> > utilization in 'wa' (wa stands for "I/O wait state"). I record a lot of HD<br>> > content so I have two 250 gig drives and I use LVM to make the two drives<br>> > appear as one to mythtv. One of these two drives is a refurb (didn't<br>> > realize it until after I bought it) and I suspect that I'm only seeing the<br>> > high wa utilization when I'm accessing the refurb drive.<br>> ><br>> > How can I verify which drive a show is stored on in a LVM enviroment? Any<br>> > other ideas on what could be causing wa to go sky high? Trying to playback<br>> > a show with the CPU hammered like this doesn't work very well.<br>> ><br>><br>> I don't know what makes you so quick to blame
the refurb drive, I<br>> don't think there's any particular reason it should be any more prone<br>> to trouble than a new one. The only drive I have ever had die on me<br>> was new, and I use a lot of refurbed drives.<br><br>I didn't have this problem before I added the refurb drive. Odds are its either<br>the drive or the fact that I'm using LVM. I just need a way to verify which is<br>the issue.<br><br>><br>> I've read that LVM has a lot of overhead, more than it has any right<br>> to have. I have a pair of 250GB drives running as a software RAID0<br>> array and they work just fine, I had a lot of problems when I tried<br>> LVM, although I am using the system for just SD.<br><br>If the LVM overhead is what is causing my high wa cpu usage then I don't see how<br>LVM ever gained any popularity. Here is a good example of the problem, this is<br>happening when I run mythtranscode on a SD show:<br><br>backend:~# dstat
-a<br>----total-cpu-usage---- -disk/total -net/total- ---paging-- ---system-- ---load-avg---<br>usr sys idl wai hiq siq|_read write|_recv _send|__in_ _out_|_int_ _csw_|_1m_ _5m_ 15m_<br> 14 2 72 12 0 0| 0 0 | 0 0 | 0 0 | 0 0 |2.41 2.36 1.42<br> 3 1 0 96 0 0|4740k 0 | 192B 2468B| 0 0 | 367 250 |2.41 2.36 1.42<br> 1 1 0 98 0 0|3048k 0 | 64B 362B| 0 0 | 351 149 |2.41 2.36 1.42<br> 0 0 0 100 0 0|
0 4096B| 64B 362B| 0 0 | 329 51 |2.38 2.35 1.42<br> 0 0 0 97 0 3| 0 96k| 64B 346B| 0 0 | 331 52 |2.38 2.35 1.42<br> 4 1 0 95 0 0|4100k 4096B| 64B 346B| 0 0 | 360 195 |2.38 2.35 1.42<br> 4 2 0 94 0 0|6560k 0 | 64B 362B| 0 0 | 383 274 |2.38 2.35 1.42<br> 5 1 0 93 1 0|8200k 0
| 64B 362B| 0 0 | 394 326 |2.38 2.35 1.42<br> 4 2 0 94 0 0|6152k 4096B| 64B 362B| 0 0 | 377 267 |2.35 2.34 1.42<br> 0 0 0 100 0 0| 0 0 | 64B 362B| 0 0 | 328 49 |2.35 2.34 1.42<br> 0 0 0 100 0 0| 128k 20k| 64B 346B| 0 0 | 333 57 |2.35 2.34 1.42<br> 1 0 0 99 0 0| 256k 0 | 64B 346B| 0 0 |
330 59 |2.35 2.34 1.42<br> 6 4 0 90 0 0|10.4M 0 | 64B 346B| 0 0 | 413 403 |2.35 2.34 1.42<br> 5 1 0 93 1 0|13.0M 16k| 128B 850B| 0 0 | 600 566 |2.32 2.34 1.42<br> 10 6 0 85 0 0|7812k 0 | 128B 954B| 0 0 | 234 324 |2.32 2.34 1.42<br> 1 0 0 99 0 0| 644k 0 | 234B 898B| 0 0 | 339 129 |2.32 2.34 1.42<br>
^^^^^<br><br>My cpu has been pegged due to wa for 10 minutes now.<br><br><br>> I'm not sure how to discover which drive of an LVM array your file is stored<br>> on, but I believe it will use all of the capacity of the "first" drive before<br>> it stores anything on the second, so if this is a fairly new system it would<br>> be reasonable to assume your second drive is not yet being used if the total<br>> is less than 250GB.<br><br>I added the second drive in time for the winter olympics so I have more that<br>250G of recorded content.<br><br>Thanks<br>Daniel<br><br>_______________________________________________<br>mythtv-users mailing list<br>mythtv-users@mythtv.org<br><a target="_blank" href="http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users">http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users</a><br></div></div></div></div></body></html>