Decrease in disk performance after partitioning and encryption, is this much of a drop normal?
- by Biohazard
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
