Timothy Miller wrote:
> I'm attempting to get some idea of how much overhead ext3 causes me on
> my workstation at home. Furthermore, I'm trying to determine what sort
> of advantage I'm really getting from my 3ware RAID controller (model
> 7000-2, configured for RAID1) over single disks.
3w 6400 (ATA/66), IBM DTLA-307020 (2MB, 7200RPM), Athlon K7 Model2 @880MHz,
2.4.26-pre5, ext3:
abit:~ > hdparm -tT /dev/sdb1
/dev/sdb1:
Timing buffer-cache reads: 644 MB in 2.00 seconds = 322.00 MB/sec
Timing buffered disk reads: 100 MB in 2.89 seconds = 34.60 MB/sec
abit:~ > /usr/bin/time dd if=/dev/sdb1 of=/dev/null bs=1k
104391+0 records in
104391+0 records out
: dd if=/dev/sdb1 of=/dev/null bs=1k
: 3.01 0:03.01 s 0.70 u 0.04 c 24% mapf 112 mipf 12
abit:~ > /usr/bin/time dd if=/dev/zero of=/dev/sdb1 bs=1k count=104391
104391+0 records in
104391+0 records out
: dd if=/dev/zero of=/dev/sdb1 bs=1k count=104391
: 4.49 0:04.49 s 1.04 u 0.05 c 24% mapf 112 mipf 12
Raw writes ~ 67% raw reads. Same disk, software raid0 mounted
ext3,data=writeback:
abit:~ > hdparm -tT /dev/md0
/dev/md0:
Timing buffer-cache reads: 628 MB in 1.99 seconds = 315.58 MB/sec
Timing buffered disk reads: 204 MB in 3.01 seconds = 67.77 MB/sec
Note after many years and configurations I no longer use native 3w RAID.
0 because the disk cannot be sub-partitioned,
1 because the mirror half is not portable to another controller,
5 because there's no real cache on the 6400 and so no performance.
As a straight controller however, unbeatable.
abit:~ > fdisk -l
Disk /dev/sda: 255 heads, 63 sectors, 2501 cylinders
Units = cylinders of 16065 * 512 bytes
Device Boot Start End Blocks Id System
/dev/sda1 * 1 13 104391 83 Linux
/dev/sda2 14 45 257040 82 Linux swap
/dev/sda3 46 2500 19719787+ 5 Extended
/dev/sda5 46 306 2096451 fd Linux raid autodetect
/dev/sda6 307 457 1212876 fd Linux raid autodetect
/dev/sda7 458 1248 6353676 fd Linux raid autodetect
/dev/sda8 1249 2500 10056658+ fd Linux raid autodetect
Disk /dev/sdb: 255 heads, 63 sectors, 2501 cylinders
Units = cylinders of 16065 * 512 bytes
Device Boot Start End Blocks Id System
/dev/sdb1 * 1 13 104391 83 Linux
/dev/sdb2 14 45 257040 82 Linux swap
/dev/sdb3 46 2500 19719787+ 5 Extended
/dev/sdb5 46 306 2096451 fd Linux raid autodetect
/dev/sdb6 307 457 1212876 fd Linux raid autodetect
/dev/sdb7 458 1248 6353676 fd Linux raid autodetect
/dev/sdb8 1249 2500 10056658+ fd Linux raid autodetect