Question: I am seeing only 50MB/s reads:

```
ensnare@box:~$ sudo hdparm -tT /dev/sda
[sudo] password for ensnare:

/dev/sda:
 Timing cached reads:   4592 MB in  2.00 seconds = 2296.48 MB/sec
 Timing buffered disk reads:  192 MB in  3.90 seconds =  49.24 MB/sec

```

The array is already rebuilt and operational. Is this kind of slow performance normal? Anything I can do to make it faster? There weren't too many options in the controller configuration. Thanks.

Answer: 
Please take a look at the following info:

The default cache policy on a physical disk is Enabled in SATA drives and Disabled on SAS drives. When physical disk caching is Enabled, disk I/O performance is improved, but a power outage or equipment failure might result in data loss or corruption. 

NOTE: It is recommended that you use a backup power source for all Dell production systems. 

On a PERC H200 card, caching is forced to be disabled for all physical disks configured into a virtual disk, regardless of the drive type and default drive settings.”

<http://support.dell.com/support/edocs/storage/storlink/h200/en/ug/html/features.htm>
The H200 controller disables all disk caching built into the drives by default. 

If the server has battery backup you can enable basic drive caching on the Logical Volumes without risk.

Goto www.LSI.com (The controller is made by LSI) and download and install MegaRAID Storage Manager.

Highlight the Virtual Raid Volume, right click, properties. Enable Cache and save.

You have to do this on every logical raid volume.

Your performance difference is incredible.