Which SSD

[wizard10000]

Re: Which SSD

I would like to add your initial reported boot time seemed longish to me. I assumed it was because you hadn't taken the time to align and optimize for SSD's but it seems more likely now that is was the faulty hardware all along.

My netbook with an average Patriot SSD is power button-to-desktop in about 19 secs. Although it is not running Kubuntu so a direct comparison is unfair. I have Bodhi linux on that one - a light weight Ubuntu based distro with Enlightenment as the DE.

Yeah, I couldn't get that SSD up over 125mb/sec - I'd changed the scheduler to noop right before it started writing garbage and thought that might be the problem but that wasn't it.

Doing the research everybody seems to disagree with me on the performance benefit of aligned partitions. I'm guessing when I benchmarked the Corsair the partition might have been aligned improperly as the numbers don't lie and everybody else is getting significantly better results than I did.

Time to go wipe out my desktop PC

[dibl]

Re: Which SSD

Here's the partitioning and the /etc/fstab from my netbook with the 40GB SSD, in case it is helpful to anyone:

root@tosh205:/home/don# fdisk -lu

Disk /dev/sda: 40.0 GB, 40018599936 bytes
32 heads, 32 sectors/track, 76329 cylinders, total 78161328 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00042576

  Device Boot   Start     End   Blocks  Id System
/dev/sda1      1024   9438207   4718592  83 Linux
/dev/sda2     9438208  13630463   2096128  82 Linux swap / Solaris
/dev/sda3    13630464  78160895  32265216  83 Linux


root@tosh205:/home/don# cat /etc/fstab
UUID=42e0cce2-17f9-4452-ab24-f40d79e18ebc   /          ext4    defaults,noatime,errors=remount-ro,barrier=0,discard,commit=120 0 1
UUID=64097124-3a9a-45e1-a051-d470805bab1d   none         swap    sw 0 0
UUID=57281ba2-b8a0-4c5c-ae4f-a1048408752c   /home        ext4    defaults,noatime,errors=remount-ro,barrier=0,discard,commit=120 0 2
none                     /tmp         tmpfs   defaults,noatime,mode=1777 0 0
none                     /var/tmp       tmpfs   defaults,noatime 0 0
none                     /var/log       tmpfs   defaults,noatime 0 0
none                     /var/spool      tmpfs   defaults,noatime 0 0

To do the partitioning with alignment to 512K cylinders, I followed this guide: http://www.ocztechnologyforum.com/fo...l=1#post373226

[wizard10000]

Re: Which SSD

Interesting.

ext3 and 4 filesystems have barriers disabled by default but I don't think the fstab entry is gonna hurt anything.

Have you played with the I/O scheduler at all? Here are a couple of pretty interesting reads -

http://ubuntuforums.org/showthread.php?t=1464706

and one off the kernel mailing list but it's almost a couple years old -

http://www.gossamer-threads.com/list...kernel/1060090

My understanding is that the CFQ scheduler is supposed to detect SSDs and adjust appropriately but testing doesn't always bear that out. As always, YMMV.

[dibl]

Re: Which SSD

Right, I think I just got lazy and left the barriers=0 option in there. It could come out.

I did change the I/O scheduler for both my desktop SSD and my netbook, to deadline. Here's more "tweaking" info from OCZ forum: http://www.ocztechnologyforum.com/fo...-and-alignment

But I have never done any benchmarking to see if one tweak or another provides a measurable performance difference. I tend to study the advice, and the quality of the rationale behind it, and then just pick a setting and go with it. Life is short ... possible tweaks are nearly infinite ... got better stuff to do than twiddle these things all day.


EDIT: for fun, here is the hdparm -tT output for the netbook:

root@tosh205:/home/don# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:  1330 MB in 2.00 seconds = 664.84 MB/sec
 Timing buffered disk reads: 372 MB in 3.01 seconds = 123.51 MB/sec

No wonder it boots so fast!

EDIT #2: and here it is for the OCZ Revodrive in my desktop:

root@aptosidbox:/home/don# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:  18534 MB in 2.00 seconds = 9276.85 MB/sec
 Timing buffered disk reads: 660 MB in 3.01 seconds = 219.45 MB/sec

It boots fast too.

[wizard10000]

Re: Which SSD

EDIT: for fun, here is the hdparm -tT output for the netbook:

root@tosh205:/home/don# hdparm -tT /dev/sda

/dev/sda:
 Timing cached reads:  1330 MB in 2.00 seconds = 664.84 MB/sec
 Timing buffered disk reads: 372 MB in 3.01 seconds = 123.51 MB/sec

No wonder it boots so fast!

That's about what I was getting with the Agility2 minus the @#$% write errors

The 500gb Samsung I just put back in my netbook now runs just a hair over 100mb/sec read and write. Not bad for a 2.5" drive

[dibl]

Re: Which SSD

I have a pair of WD1002FAEX hard drives in a BTRFS filesystem, connected to a "SATA 3" (i.e. a 6GiB/s) Marvell 9128 controller. They are very fast -- as per:

root@aptosidbox:/home/don# hdparm -tT /dev/sdc

/dev/sdc:
 Timing cached reads:  18558 MB in 2.00 seconds = 9286.34 MB/sec
 Timing buffered disk reads: 372 MB in 3.00 seconds = 123.80 MB/sec

That would be a good choice for a server setup. Mine only serves the other computer across the room.

[wizard10000]

Re: Which SSD

That would be a good choice for a server setup.

Yup.

I recently disapproved a request for a print server with a five-disk, 15k rpm array - when I asked the sysadmin why he said he wanted as much disk throughput as he could get. I politely asked him if he was insane

I explained to the sysadmin that his disk subsystem didn't have to talk faster than his NIC and that if he'd roll the hardware back to a three-disk 7200 rpm array I'd approve the purchase.

There. I saved y'all some tax dollars

[dibl]

Re: Which SSD

There. I saved y'all some tax dollars

Thanks wiz -- we need all we can save! :P

[wizard10000]

Re: Which SSD

I would like to add your initial reported boot time seemed longish to me. I assumed it was because you hadn't taken the time to align and optimize for SSD's but it seems more likely now that is was the faulty hardware all along.

Got the SSD back yesterday and threw it in the netbook. grub to kdm greeter time is ~16 sec but this time with no errors

wizard@wizard-netbook:~$ sudo hdparm -tT /dev/sda
[sudo] password for wizard:

/dev/sda:
Timing cached reads: 1206 MB in 2.00 seconds = 602.94 MB/sec
Timing buffered disk reads: 370 MB in 3.00 seconds = 123.23 MB/sec
wizard@wizard-netbook:~$


Reads have averaged 123-126 mb/sec which is less than half the rated throughput of the SSD. More info -

wizard@wizard-netbook:~$ sudo fdisk -l

Disk /dev/sda: 60.0 GB, 60022480896 bytes
32 heads, 32 sectors/track, 114483 cylinders
Units = cylinders of 1024 * 512 = 524288 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000ceb19

Device Boot Start End Blocks Id System
/dev/sda1 * 2 40962 20972032 83 Linux
/dev/sda2 40963 45315 2228736 82 Linux swap / Solaris
/dev/sda3 45316 114483 35414016 83 Linux
wizard@wizard-netbook:~$


and

wizard@wizard-netbook:~$ cat /etc/default/grub
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=3
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="selinux=0 apparmor=0 elevator=noop"
GRUB_CMDLINE_LINUX="selinux=0 apparmor=0 elevator=noop"

and

wizard@wizard-netbook:~$ cat /etc/fstab
# /etc/fstab: static file system information.
#
# Use 'blkid -o value -s UUID' to print the universally unique identifier
# for a device; this may be used with UUID= as a more robust way to name
# devices that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
# / was on /dev/sda1 during installation
UUID=690541da-1388-4814-bba2-7e78ec22d06d / ext4 errors=remount-ro,noatime,discard,commit=120 0 1
# /home was on /dev/sda3 during installation
UUID=2f1807ca-8990-40ca-bcc1-d3fb6375e2eb /home ext4 noatime,discard,commit=120 0 2
# swap was on /dev/sda2 during installation
UUID=91347c22-f774-4630-a642-95a10592838c none swap sw 0 0

It appears to me the bottleneck is *not* the SSD. The 500gb Samsung drive that was in my netbook will sustain 100mb/sec reads and writes so the SSD is about 25% faster and boot times reflect that.

Let's see what bonnie says -

wizard@wizard-netbook:~$ bonnie++ -d /tmp/bonnie
Writing a byte at a time...done
Writing intelligently...done
Rewriting...done
Reading a byte at a time...done
Reading intelligently...done
start 'em...done...done...done...done...done...
Create files in sequential order...done.
Stat files in sequential order...done.
Delete files in sequential order...done.
Create files in random order...done.
Stat files in random order...done.
Delete files in random order...done.
Version 1.96 ------Sequential Output------ --Sequential Input- --Random-
Concurrency 1 -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
wizard-netbook 4G 129 99 131803 74 63745 40 605 99 149268 40 9516 425
Latency 111ms 330ms 292ms 22326us 9325us 15072us
Version 1.96 ------Sequential Create------ --------Random Create--------
wizard-netbook -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
16 3140 18 +++++ +++ 22437 88 17093 91 +++++ +++ 22775 88
Latency 48539us 6585us 2496us 538us 113us 1518us
1.96,1.96,wizard-netbook,1,1308800134,4G,,129,99,131803,74,63745,40 ,605,99,149268,40,9516,
425,16,,,,,3140,18,+++++,+++,22437,88,17093,91,+++ ++,+++,22775,88,111ms,
330ms,292ms,22326us,9325us,15072us,48539us,6585us, 2496us,538us,113us,1518us
wizard@wizard-netbook:~$


and

wizard@wizard-netbook:~$ sudo seeker /dev/sda
[sudo] password for wizard:
Seeker v2.0, 2007-01-15, http://www.linuxinsight.com/how_fast_is_your_disk.html
Benchmarking /dev/sda [57241MB], wait 30 seconds..............................
Results: 3814 seeks/second, 0.26 ms random access time

[dibl]

Re: Which SSD

Good -- looks like you got a good replacement (or repair job).

Have you seen the specs for the Vertex 3? Almost enough to make me go find a job!

Here's a nice little exercise for your SSD, that I found the other day on another forum, in another language. Don't forget to erase the 1GB "tempfile" when you are done with it. The example figures are from his Vertex 3. My Revodrive does about 6.3 GB/s.

#How to use dd to benchmark a hard drive or SSD


$ cd /path/to/hdd_or_SSD_partition
$ dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 2.18232 s, 492 MB/s


Now we clear the buffer cache to get the speed of reading directly from the disk:
# echo 3 > /proc/sys/vm/drop_caches
$ dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 2 , 55234 s, 421 MB/s


Now we leave the last read file in the buffer cache and measure its copy speed:
$ dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.122594 s, 8.8 GB/s

For maximum accuracy, run the last command 5 times and average the values.

[wizard10000]

Re: Which SSD

Good -- looks like you got a good replacement (or repair job).

Have you seen the specs for the Vertex 3? Almost enough to make me go find a job!

Here's a nice little exercise for your SSD, that I found the other day on another forum, in another language. Don't forget to erase the 1GB "tempfile" when you are done with it. The example figures are from his Vertex 3. My Revodrive does about 6.3 GB/s.

I gotta say I was pleased with OCZ's RMA process. I shipped the drive to California via UPS ground last Monday - they received it on Friday. The replacement drive was shipped FedEx from Taiwan the following Monday and I got it on Wednesday morning.

If you go find a job you'd best go find a SATA 3 controller as well

I've used dd to benchmark drives before but the drop_caches was new to me.

I'm still not tickled with this netbook's SSD performance but the bottleneck ain't the SSD.

wizard@wizard-netbook:~$ sudo -i
[sudo] password for wizard:
root@wizard-netbook:~# cd /tmp
root@wizard-netbook:/tmp# dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 7.99121 s, 134 MB/s
root@wizard-netbook:/tmp# echo 3 > /proc/sys/vm/drop_caches
root@wizard-netbook:/tmp# dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.37396 s, 781 MB/s
root@wizard-netbook:/tmp# dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.30591 s, 822 MB/s
root@wizard-netbook:/tmp# rm -f tempfile


Subsequent runs looked like this -

root@wizard-netbook:/tmp# dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.30625 s, 822 MB/s
root@wizard-netbook:/tmp# dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.30755 s, 821 MB/s
root@wizard-netbook:/tmp# dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.35393 s, 793 MB/s
root@wizard-netbook:/tmp# dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 1.34128 s, 801 MB/s

[dibl]

Re: Which SSD

root@wizard-netbook:/tmp# dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 7.99121 s, 134 MB/s

That is an odd-looking number. Even on a 4-year old WD1500 raptor hdd, I get this:

don@susansid:~$ dd if=/dev/zero of=tempfile bs=1M count=1024 conv=fdatasync,notrunc
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 13.4085 s, 80.1 MB/s
don@susansid:~$ sux
Password: 
root@susansid:/home/don# echo 3 > /proc/sys/vm/drop_caches
root@susansid:/home/don# exit
exit
don@susansid:~$ dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 13.6744 s, 78.5 MB/s
don@susansid:~$ dd if=tempfile of=/dev/null bs=1M count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB) copied, 0.353903 s, 3.0 GB/s

And why is your "dd" command not calculating GB/s speed for the last output?

p.s. MY Asus P6X58D-E motherboard does have the Marvell 9128 "SATA 3" chip, but I have a pair of WD1002FAEX drives on it, so both the fast channels are used already.

[wizard10000]

Re: Which SSD

...And why is your "dd" command not calculating GB/s speed for the last output?

I'm guessing because the speed was < 1GB

[dibl]

Re: Which SSD

I'm guessing because the speed was < 1GB

Well, ... duhhhhh.

Yeah, I think maybe there's a bottleneck elsewhere, like the controller chip.

[wizard10000]

Re: Which SSD

Yeah, I think maybe there's a bottleneck elsewhere, like the controller chip.

Makes sense. The netbook runs pretty well, and after I install the Intel WLAN card I mentioned in another thread I'll be done tweaking netbooks. Considering I got the netbook for $179 on a Black Friday special and have spent $40 for a 2GB DIMM, $129 on the SSD and $24 on the 802.11n card I don't think this netbook owes me anything.

I do wish I could have found a half-height WLAN card that also had bluetooth but the only ones I could find had less-than-optimal Broadcom chipsets.

Oh, well. My itty bitty USB bluetooth dongle works just fine.