[PVE-User] I/O issues

[Shain Miley]

I just looked at dmesg on this server and I see the line:

sd 0:1:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't 
support DPO or FUA
sd 0:1:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't 
support DPO or FUA

I am going to try to enable the write cache and see if I/O gets any 
better. 

Thanks,

Shain


Shain Miley wrote:
> I have been trying to figure out why we are seeing some the commands on 
> an Oracle VM go so slowly.  I believe that the issue is an I/O one.  
> Below is the output from vztop (with some iowait numbers that look high 
> to me).  The disks are 300GB raid 1 SAS drives.
>
> Also here is the output from 'pveperf':
>
> proxmox5:/usr/local# pveperf
> CPU BOGOMIPS:      42564.52
> REGEX/SECOND:      649026
> HD SIZE:           68.41 GB (/dev/pve/root)
> BUFFERED READS:    61.31 MB/sec
> AVERAGE SEEK TIME: 32.08 ms
> FSYNCS/SECOND:     94.04
> DNS EXT:           11.48 ms
>
>
> proxmox5:/sys/block/sda/queue# vztop
>
>  14:27:42  up 10 days,  1:42,  1 user,  load average: 3.86, 3.93, 3.90
> 324 processes: 321 sleeping, 3 running, 0 zombie, 0 stopped
> CPU0 states:   3.2% user   0.1% system    0.0% nice  33.1% iowait  62.4% 
> idle
> CPU1 states:   0.1% user   0.2% system    0.0% nice  15.3% iowait  83.3% 
> idle
> CPU2 states:   5.0% user   1.1% system    0.0% nice  33.2% iowait  60.0% 
> idle
> CPU3 states:   0.4% user   0.1% system    0.0% nice  28.0% iowait  70.4% 
> idle
> CPU4 states:   5.3% user   0.2% system    0.0% nice  30.1% iowait  63.4% 
> idle
> CPU5 states:   0.1% user   0.1% system    0.0% nice  11.4% iowait  87.3% 
> idle
> CPU6 states:   6.2% user   0.1% system    0.0% nice  27.0% iowait  66.1% 
> idle
> CPU7 states:   0.2% user   0.3% system    0.0% nice  42.3% iowait  56.1% 
> idle
> Mem:  32920024k av, 4895028k used, 28024996k free,       0k shrd,    
> 6336k buff
>       2330236k active,             513568k inactive
> Swap: 32505848k av,  240172k used, 32265676k free                  
> 775456k cached
>
>   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME CPU COMMAND
>  7532 #501      20   0  606M 180M  177M S     8.3  0.5   0:10   4 oracle
>  6957 #501      20   0  606M 196M  193M R     4.3  0.6   0:11   6 oracle
> 27762 root      20   0 1381M 392M 23596 S     3.5  1.2  11:31   7 java
> 14850 root      20   0 69948 4708  2924 S     3.3  0.0  48:38   0 httpd
> 13669 #501      20   0  612M 179M 34608 S     2.9  0.5   2:49   5 java
>  6743 #501      20   0  609M 209M  204M R     1.9  0.6   0:40   2 oracle
>  6883 #501      20   0  606M 206M  203M S     0.3  0.6   0:50   6 oracle
> 12822 root      20   0  7384 1828   872 S     0.3  0.0   0:00   3 sendmail
> 17058 #501      20   0  606M  64M 62748 S     0.3  0.2   0:00   1 oracle
> 17263 root      20   0 18284 1656   996 R     0.3  0.0   0:00   7 vztop
>     1 root      20   0 10316   88    56 S     0.0  0.0   0:04   1 init
>
>
> Any thoughts would be great.
>
> Thanks,
>
> Shain
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