Hello everyone,
I'm somewhere between a linux noob and novice. So please don't assume I've covered all my bases.
I've got Ubuntu server 11.04 on a micro SD in a USB reader as the HD. My storage is a software RAID1 set consisting of two Samsung F4EG HD155UI 1.5GB dries. My read speed is fine, but my write speed is less than 1Mbps. What should I do?

Thanks!

OK...It may be an issue with the 4K sectors: http://www.sfnomad.com/?p=68

Could this be causing normal reads but very slow writes?

It's unlikely to make a huge difference in most circumstances, I believe that it's only certain usage scenarios that you could notice the sector size making a large difference (lot's of tiny writes. It will not make a performance difference unless in a particular performance sensitive scenario.

check how the RAID is mounted. What are the switches in /etc/fstab ?

Here's what I found:

# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
/dev/sdc1 / ext4 errors=remount-ro 0 1
# swap was on /dev/sdc5 during installation
UUID=xxxx none swap sw 0 0
/dev/md0 /mnt/RAID1 ext4 grpid,nosuid,sync,noexec,nodev 0 0
~

FYI...I'm using Webmin for management.

Thanks!

ouch @ webmin.

You will certainly gain a great deal if you wish to learn about linux, by using the commandline.

yes by the looks of it you have the raid set mounted as synchronous. I suggest you at least try changing the 'sync' to 'async' you might also just want to try changing 'grpid,nosuid,sync,noexec,nodev' to 'defaults'

i think this may be the problem, if not you can always revert. Let me know how it goes.

I first noticed when a simple stock update on an commerce website was taking 14 mins compared to 30 seconds on my local VM. Running sql-bench takes forever and the wait is at 100% when running it.

Here's atop when running sql-bench run-al-tests (may have to copy and paste into a text editor using courier as the font):


PRC | sys 0.08s | | user 0.04s | | | | | #proc 167 | | #zombie 0 | | clones 0 | | | | | #exit 0 |
CPU | sys 10 | | user 0% | | irq 0% | | | | idle 304% | | wait 95% | | | | steal 0% | | guest 0% |
cpu | sys 0% | | user 0% | | irq 0% | | | | idle 98% | | cpu001 w 2% | | | | steal 0% | | guest 0% |
cpu | sys 0% | | user 0% | | irq 0% | | | | idle 7% | | cpu000 w 93% | | | | steal 0% | | guest 0% |
cpu | sys 0% | | user 0% | | irq 0% | | | | idle 100% | | cpu002 w 0% | | | | steal 0% | | guest 0% |
CPL | avg1 2.181 | | avg5 2.11 | | | avg15 2.02 | | | | csw 2738 | | intr 1541 | | | | | numcpu 4 |
MEM | tot 11.6G | | free 10.3G | | cache 149.0M | dirty 0.7M | | buff 129.0M | | slab 56.6M | | | | | | | |
SWP | tot 3.7G | | free 3.7G | | | | | | | | | | | | vmcom 4.8G | | vmlim 9.5G |
LVM | vg00-var | | busy 100% | | read 0 | write 644 | | KiB/r 0 | | KiB/w 4 | | MBr/s 0.00 | MBw/s 0.25 | | avq 1.11 | | avio 15.5 ms |
MDD | md3 | | busy 0% | | read 0 | write 712 | | KiB/r 0 | | KiB/w 3 | | MBr/s 0.00 | MBw/s 0.25 | | avq 0.00 | | avio 0.00 ms |
DSK | sda | | busy 64% | | read 0 | write 295 | | KiB/r 0 | | KiB/w 8 | | MBr/s 0.00 | MBw/s 0.25 | | avq 1.10 | | avio 21.8 ms |
DSK | sdb | | busy 63% | | read 0 | write 302 | | KiB/r 0 | | KiB/w 8 | | MBr/s 0.00 | MBw/s 0.25 | | avq 1.09 | | avio 20.8 ms |
NET | transport | tcpi 7 | | tcpo 7 | udpi 0 | | udpo 0 | tcpao 0 | | tcppo 0 | tcprs 0 | | tcpie 0 | tcpor 0 | | udpnp 0 | udpip 0 |
NET | network | | ipi 7 | | ipo 7 | ipfrw 0 | | deliv 7 | | | | | | | icmpi 0 | | icmpo 0 |
NET | eth0 0% | | pcki 76 | pcko 7 | | si 0 Kbps | so 2 Kbps | | coll 0 | | mlti 0 | erri 0 | | erro 0 | drpi 0 | | drpo 0 |
|
PID RUID EUID THR SYSCPU USRCPU VGROW RGROW RDDSK WRDSK ST EXC S CPUNR CPU CMD 1/1
2104 root root 1 0.03s 0.021 0K 0K 0K 0K -- - S 1 0% htop
2061 mysql mysql 8 0.01s 0.011 0K 0K 0K 560K -- - S 0 0% mysqld
2119 root root 1 0.01s 0.01s 0K 0K 0K 0K -- - R 1 0% atop
34 root root 1 0.01s 0.00s 0K 0K 0K 0K -- - S 0 0% kblockd/0
373 root root 1 0.01s 0.00s 0K 0K 0K 0K -- - S 1 0% md3_raid1
826 root root 1 0.01s 0.00s 0K 0K 0K 152K -- - D 0 0% jbd2/dm-1-8
1418 postfix postfix 1 0.00s 0.00s 0K 0K 0K 0K -- - S 0 0% qmgr
1405 root root 1 0.00s 0.00s 0K 0K 0K 0K -- - S 2 0% master

Also here's the fstab:

/dev/md1 / ext3 defaults 1 1
/dev/sda2 none swap sw
/dev/sdb2 none swap sw
/dev/vg00/usr /usr ext4 defaults 0 2
/dev/vg00/var /var ext4 defaults,usrquota 0 2
/dev/vg00/home /home ext4 defaults,usrquota 0 2
devpts /dev/pts devpts gid=5,mode=620 0 0
none /proc proc defaults 0 0
none /tmp tmpfs defaults 0 0

iSpaZZZ^,
Setting the RAID mount to defaults did the trick!
Thank you very much!

What's the best way to get my RAID1 drive set to go to sleep. I have done this before with hdparm, but I'm not able to figure it out now. Any advise?

Thanks!