I have a server that I only have remote access to. Earlier in the week I repartitioned the 2 disk raid as follows:

Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/sda1_crypt
                      363G  1.8G  343G   1% /
tmpfs                 2.0G     0  2.0G   0% /lib/init/rw
udev                  2.0G  140K  2.0G   1% /dev
tmpfs                 2.0G     0  2.0G   0% /dev/shm
/dev/sda5             461M   26M  412M   6% /boot
/dev/sda7             179G  8.6G  162G   6% /data

The raid consists of 2 x 300gb SAS 15k disks.

Prior to the changes I made, it was being used as a single unencrypted root parition and hdparm -t /dev/sda was giving readings around 240mb/s, which I still get if I do it now:

/dev/sda:
Timing buffered disk reads: 730 MB in  3.00 seconds = 243.06 MB/sec

Since the repartition and encryption, I get the following on the separate partitions:

Unencrypted /dev/sda7:

/dev/sda7:
Timing buffered disk reads: 540 MB in  3.00 seconds = 179.78 MB/sec

Unencrypted /dev/sda5:

/dev/sda5:
Timing buffered disk reads: 476 MB in  2.55 seconds = 186.86 MB/sec

Encrypted /dev/mapper/sda1_crypt:

/dev/mapper/sda1_crypt:
Timing buffered disk reads: 150 MB in  3.03 seconds =  49.54 MB/sec

I expected a drop in performance on the encrypted partition, but not that much, but I didn't expect I would get a drop in performance on the other partitions at all.

The other hardware in the server is:

2 x Quad Core Intel(R) Xeon(R) CPU E5405 @ 2.00GHz and 4gb RAM

$ cat /proc/scsi/scsi            
Attached devices:
Host: scsi0 Channel: 00 Id: 32 Lun: 00
  Vendor: DP       Model: BACKPLANE        Rev: 1.05
  Type:   Enclosure                        ANSI  SCSI revision: 05
Host: scsi0 Channel: 02 Id: 00 Lun: 00
  Vendor: DELL     Model: PERC 6/i         Rev: 1.11
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: HL-DT-ST Model: CD-ROM GCR-8240N Rev: 1.10
  Type:   CD-ROM                           ANSI  SCSI revision: 05

I'm guessing this means the server has a PERC 6/i RAID controller?

The encryption was done with default settings during debian 6 installation. I can't recall the exact specifics and am not sure how I go about finding them?

Thanks