Linux - Tips, tweaks and alignment

[b2bde4]

The main purpose behind this thread is to collect all the suggestions, the discussion and the benchmarks in one convenient Linux thread.

This guide assumes your SSD is located at /dev/sda

Parts of this guide could be used even though you're not planning to use Linux. See this post made by khelvan for more details.
Short extract from the post made by khelvan

The information below will allow any user to take advantage of the information above without having to install Linux. In addition, it will enable you to work with a computer that has no working hard disk (be it SSD or older HDD).

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Wiper and manual TRIM
Take a look at this thread for further information.
(Link)


In-kernel automatic TRIM

• You need at least kernel version 2.6.33 or later.
• You need at least firmware version 1.5. Firmware version 1.4 works, but it is too slow.

This thread covers most of the findings on the subject. (Link)(First relevant post)

For Ubuntu users, you need to manually update your kernel if you want automatic trim. The first Ubuntu version to support this feature will probably be Ubuntu 10.10 which will be released at the end of October 2010. Manual trim will of course still be supported through wiper.sh as with the previous firmware (1.4).


Check firmware revision
To check the firmware revision on Linux, you could use sudo hdparm -I /dev/sda. The final character denotes which disk to examine.


S.M.A.R.T (wiki)

Smartmontools with native S.M.A.R.T-support for Vertex and Agility ssd's.

It seems that there is a new release of smartmontools and now one of the released commits give us full native S.M.A.R.T-support for OCZ Vertex and Agility drives.

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Ubuntu Picture Guide

Ubuntu Picture Guide

Trying out Linux is easy. This guide will show you the ease of using Ubuntu. The only thing you need, to try it out, is a Live CD (wiki). The default Ubuntu desktop CD is a Live CD. An Ubuntu Live CD contain all the tools you need to align your partitions. Those tools could even be used to prepare for your Windows installation.

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Alignment

Partition alignment for OCZ Vertex in Linux

This guide will show you how to set up general alignment for use with Linux.
Tweaking some of the values used will yield different results.

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Creating aligned partitions using a GUID partition table

This is a guide for anyone going to use GPT.

GPT is a partition table which replaces the legacy MBR. Since fdisk doesn't support GPT we will have to use a tool called parted. To use this tool we need to understand some of the basic maths behind aligning partitions. This guide shows how to manually create aligned partitions based on sectors. GPT is supported by GRUB 2 used by default in a clean installation of Ubuntu 9.10.

• This guide will create a new GUID partition table.
• Create a 100MiB partition.
• Create a second partition covering the rest of the disk.

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Windows Alignment with Linux

This guide will show you how to set up "Windows alignment" using Linux. The alignment achieved should be identical to an alignment made using Windows tools. This is not the recommended procedure if your going to use Linux, though it should work just fine.

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The best tool available to create your partitions is fdisk unless your going to use a GUID partition table in which case you should follow the guide about GPT above.

These are the some of the starting options available for fdisk. The option -S is used to define a custom number of sectors per track. -H is for heads. Changing these values will effect the alignment of partitions created with this tool.
Accepted input values.

• -H Number of heads (1-255. default 255) (256 in expert mode, use at your own risk)
• -S Number of sectors (1-63, default 63)

File System
If you mount your disk with the option noatime you could lower the number of writes to your disk.

• Open /etc/fstab in your favourite text editor as root. [sudo gedit /etc/fstab]
• Locate the SSD you want to optimize.
• Identify which parameter is currently in use. Possible values are atime, noatime, realtime.
• If applicable, change the value to noatime.
• Restart system.

There are some options available for ext4/ext3.
This section is only meant as curiosa. Using it probably won't effect performance.
You could achieve write alignment using the option strip-width. The first thing you'll want to do is to make sure that the partition you're going to use starts exactly on an erase block.

Find the starting sector using [sudo fdisk -lu]. If it starts on a value that are an even multiple of 1024. Then you're ready to proceed.

[sudo mke2fs -t ext4 -E stripe-width=128 /dev/sda1]

Since the default file system sector size is 4kB, stripe-width=128 will result in 512kB alignment. The file system will now try to align each write at the start of an empty erase block.

sda1 indicates that we want to create our file system on the first partition on /dev/sda.

You could create your file system without a journal. This is not recommended as you might experience a data loss after an unclean shutdown.
[mke2fs -t ext4 -O ^has_journal /dev/sda]


Setting up a RAM disk (wiki)
Before you try this out, make sure you have plenty of free RAM.

To create a RAM drive we're going to use tmpfs.

To mount the system temp folder in tmpfs.

• Open /etc/fstab in your favourite text editor as root. [sudo gedit /etc/fstab]
• Add tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0 at the end of the file.
• Restart system.

All temporary files will now be written to your RAM instead of to your disk.
To verify this, use the command df. Search for lines begging with temps.

tmpfs                  1996928     23404   1973524   2% /tmp

This tweak could also be used to create a general purpose Ram disk.

• Create an empty folder as a root. [sudo mkdir /media/Ramdisk]
• Open /etc/fstab in your favourite text editor as root. [sudo gedit /etc/fstab]
• Add tmpfs /media/Ramdisk tmpfs defaults,noatime,mode=1777 0 0 at the end of the file.
• Restart system.
• Optional. Create a link to your newly created folder at a place of your convenience.

Some remarks:

• Some people also suggest the use of RAM disks for /var/tmp or /var/log.
  This can be done in the same way as setting up a RAM disk for /tmp
  (see b2bde4's guide). Note that the system will be unable to umount
  /var/log cleanly when shutting down (since the device is busy)
  but this will not harm (who cares if temporary data on the RAM disk
  is lost?)

Move Firefox cache to RAM disk
This might not be useful if you're on a very slow modem connection and restarts your computer very often.

• Open Firefox.
• Type about:config in the search bar.
• Right click on any row.
• Select New > String from the popup menu.
• Add browser.cache.disk.parent_directory and press enter.
• Close Firefox.

Use about:cache to verify.


I/O Scheduler (wiki)
Changing scheduler could improve the speed of the SSD.

Do not do not do not do not use the anticipatory (default for for 2.6 up to 2.6.18) scheduler or the cfq (default for 2.6.19-current) scheduler. These schedulers achieve a remarkable speedup on standard, platter hard drives by pausing after each read: usually after a process performs a read, it will read again (presumably grabbing another chunk of the same file) in quick succession. This trick will help alleviate seek times, which is the biggest detriment to hard drive performance. (note that at one point, this 'feature' of cfq was broken) You and I do not have this performance disadvantage. The noop and deadline schedulers do not perform this 'advanced logic' that serves little purpose for SSDs other than slowing them down.

However, deadline and noop are not created equal. Deadline will re-order reads and writes, attempting to decrease latency, etc. Noop will do absolute no logic of any kind - it is a simple fifo. It's really designed for people with dedicated RAID hardware that will perform all of this logic for them. Sometimes this is useful - if you have an eeepc and underclock it to 800MHz for maximum battery life, you really need every CPU cycle you can get, and noop can be a decent idea.

However, if you have a reasonably fast system, you're better served by deadline. It gives more priority to reads over writes: delays caused by waiting for io is typically caused because of a delay from reading, not writing.

To find out which schedulers are available on your system and which one is currently in use, use the command cat /sys/block/sda/queue/scheduler. The one in use is marked by [].

noop anticipatory deadline [cfq]

To temporarily change scheduler during runtime.

• Login as root [sudo -i]
• echo deadline > /sys/block/sda/queue/scheduler
• Logout the root shell [logout]

To make this change permanent you could add appropriate lines to /etc/rc.local. You could also edit /boot/grub/menu.lst.

Some remarks:

• Setting the scheduler should probably be done automatically during boot.
  If there are only SSDs in the system and no regular HDDs, one can select
  deadline globally by adding the kernel parameter elevator=deadline in the
  kernel parameter line of the boot loader.
  Another way is editing /etc/rc.local or /etc/init.d/boot.local,
  depending on the Linux distribution. There one can directly add a line
  echo deadline > /sys/block/sda/queue/scheduler
  This will only change the scheduler for the specified device, so
  this is the way to go on a mixed system with both SSDs and HDDs.

Using the kernel parameter in GRUB might not be permanent during a kernel upgrade.
Instead find the line beggining with # kopt=root=UUID= and add the parameter elevator=noop to it. Don't ever remove the starting # from this line.
When it's done, run the command sudo update-grub.


Tools
You can use hdparm to check your read speed, even though the results are somewhat limited.

sudo hdparm -t /dev/sda
sudo hdparm -t --direct /dev/sda

You could also use dd to to check your speed.

4KB reads. 0 offset (skip). Read (count) 200MB data.
sudo dd if=/dev/sda1 of=/dev/null bs=4k skip=0 count=51200
Without count, Use ^c (control-c) to abort.

Some remarks:

• If you want to know how much I/O traffic you have on the SSD, you can
  check with iostat -m -d /dev/sda. This displays MB_read and MB_wrtn
  for the given drive (measured since system startup). iostat also works
  for individual partitions. It is provided by the sysstat package.

Swap file

Some remarks:

• Kernel swappiness is a controversial topic. The standard setting (60) for
  kernel swappiness has the effect that inactive (but started) applications
  will be moved to swap after some time. If the swap partition is placed
  on a regular HDD in order to reduce wear of the SSD, then reloading the
  application from swap can take several seconds. This causes annoying
  delays and bad responsiveness of the system when you return from a
  coffee break, for example. The solution is setting kernel swappiness
  to zero, by adding a line vm.swappiness = 0 to /etc/sysctl.conf.
  A temporary change for trying out the effect is possible by calling
  echo 0 > /proc/sys/vm/swappiness (as root) from the command line.

Raid
If you want to use raid but don't have a dedicated hardware raid card, you should instead create a Linux software raid array. Don't use the integrated raid controller on your motherboard. There is nothing to be gained unless your going to dual boot from it.

If you created a raid array on Windows using Windows drivers, you probably won't be able to access it using Linux.

I just posted in another thread about issues I was having with reads being slower than writes in RAID0 and not getting quite the twice the performance of a single Vertex. In fact my reads were slower in RAID0 than in the single drive. I was getting like 220MB/s in RAID0 vs. 260-270MB/s in single drive.

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Secure Erase

On Linux, this is done as follows (assuming /dev/sda is the drive):

hdparm --security-set-pass NULL /dev/sda
hdparm --security-erase NULL /dev/sda

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Making a backup of your system and then restore it

Making a backup of your system and then restore it (Tested with Ubuntu)

Making backups of a Linux system involves a few easy steps.

• The use of a Live CD to prevent system changes during backup.
• Copy all files to a new location.
• Remember partition UUID.

Restoring the backup involves a few more steps.

• Copy backup files to their previous location.
• Restore partition UUID.
• Restore GRUB.

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[b2bde4]

When I installed my 30 GB Vertex, I follow the post made by Pigeon. I'm using Ubuntu 9.04 and the system feels fast and snappy. I probably could have made a better alignment if I where to reinstall my system today I only have one Vertex, so testing from my side will by fairly limited.

[FZ1]

Thanks, Man. I made this a sticky...

Staff: I know we are trying to reduce the amount of stickies so unstick if needed.

[khelvan]

The information below will allow any user to take advantage of the information above without having to install Linux. In addition, it will enable you to work with a computer that has no working hard disk (be it SSD or older HDD).

First, you want to download a Linux distribution in Live CD (can boot directly to CD/DVD without needing to install) format - I recommend Ubuntu for people unfamiliar with Linux:
Get Ubuntu 8.10 Intrepid Ibex here (make sure to choose 32-bit or 64-bit depending on your processor).

Next, you will want to burn the disk image to a CD or DVD. This requires a CD-R/RW or DVD-R/RW drive, and image burning software. For this I recommend the open source Infrarecorder.
Get Infrarecorder here.

With Infrarecorder all you need to do is click on the "Write image to CD/DVD" button, choose the location of your .iso file, and it will do the rest for you.

Once you have created the CD/DVD, you can insert it prior to rebooting, and you will be able to load the operating system. Simply choose the option that allows you to "Try Ubuntu" without installing, and you will then be running the O/S directly from your CD/DVD drive. Once loaded, choose Applications -> Accessories -> Terminal and then you can follow the instructions in the posts above.

For those who do have access to a CD/DVD burner but do not have a CD/DVD drive in the computer with your SSD, but do have a USB port (for instance, many netbook computers), the following guide can show you how to create an image that may be booted directly from your USB stick.
How to run the Ubuntu Live CD from a USB stick.

By the way, you can use this process to do lots of neat things such as connect to the internet when your HDD has died, scan your Windows partition with antivirus software when you suspect the boot record has a virus, take over your friends' computers when you don't know the passwords, and other fun stuff.

I hope this helps!

[drgnfang]

Look for "unetbootin" for windows. That will let you load pretty much any linux ISO on to a USB stick and have it bootable.

[TortureTest]

Some remarks:

• As far as I understand Ted Tso's guide for partition alignment,
  http://thunk.org/tytso/blog/2009/02/...se-block-size/,
  aligning according to Pidgeon's description will not automatically align the
  first partition since the first partition will automatically by displaced by one
  track for MS-DOS compatibility. However, this should not matter too much if
  the first partition is used for /boot, for example.
  
• Setting the scheduler should probably be done automatically during boot.
  If there are only SSDs in the system and no regular HDDs, one can select
  noop globally by adding the kernel parameter elevator=noop in the
  kernel parameter line of the boot loader.
  Another way is editing /etc/rc.local or /etc/init.d/boot.local,
  depending on the Linux distribution. There one can directly add a line
  echo noop > /sys/block/sda/queue/scheduler
  This will only change the scheduler for the specified device, so
  this is the way to go on a mixed system with both SSDs and HDDs.
  
• Some people also suggest the use of RAM disks for /var/tmp or /var/log.
  This can be done in the same way as setting up a RAM disk for /tmp
  (see b2bde4's guide). Note that the system will be unable to umount
  /var/log cleanly when shutting down (since the device is busy)
  but this will not harm (who cares if temporary data on the RAM disk
  is lost?)
  
• Kernel swappiness is a controversial topic. The standard setting (60) for
  kernel swappiness has the effect that inactive (but started) applications
  will be moved to swap after some time. If the swap partition is placed
  on a regular HDD in order to reduce wear of the SSD, then reloading the
  application from swap can take several seconds. This causes annoying
  delays and bad responsiveness of the system when you return from a
  coffee break, for example. The solution is setting kernel swappiness
  to zero, by adding a line vm.swappiness = 0 to /etc/sysctl.conf.
  A temporary change for trying out the effect is possible by calling
  echo 0 > /proc/sys/vm/swappiness (as root) from the command line.
  
• The FirmwareUpdateKit package offers a convenient way for running
  DOS applications (like HDDErase) in Linux without a floppy boot disk or
  bootable USB stick. To this end, one calls fuk --grub HDDERASE.EXE
  from the command line; this adds a "Firmware Update" option to the boot
  loader which can be used to invoke HDDErase.
  
• If you want to know how much I/O traffic you have on the SSD, you can
  check with iostat -m -d /dev/sda. This displays MB_read and MB_wrtn
  for the given drive (measured since system startup). iostat also works
  for individual partitions. It is provided by the sysstat package.

[b2bde4]

khelvan: Added a hint to your post.
TortureTest: Added quotes from your post.

[smacfarl]

So later on in the thread you quote Amozz from above, he explicitly outlines his procedure for alignment.

I think you could replace the first two suggestions with his outline from this entries.

http://www.ocztechnologyforum.com/fo...8&postcount=14.

You'll note that Amozz would seem to skip the first 128 in this procedure as TortureTest mentions to get around the 63 dos compatibility issue in the first track.

I would like to learn a little more about swap and I/O issues. Do you know of other threads about these things?

[b2bde4]

I think I'll add it as a general quick step guide later on. The problem with the later post is that it's missing all the explanations. That is probably why I picked the first one while saving the other one for later use.

If you mean scheduling by I/O then you could start by following the wikipedia link and then click on the links for, Completely Fair Queuing, Noop scheduler and Deadline scheduler.

I don't think I ever came across any interesting topic regarding a swap file. TortureTest mentions "Kernel swappiness" in his post. Try to do a search with this phrase in it and you'll probable find more about the topic.

[smacfarl]

So I will be installing Ubuntu, 8.10 in my case, on my purchased Vertex 30 gb drive. I am trying to figure out the best way of doing this.

Do you have any suggestions for doing the flash update to 1275 from linux?

In my set up I will use the vertex as the boot drive, this is where Ubuntu and it's apps will reside.

I will have a 1 TB sata for /usr, as well as for a swap partition there.

I was also thinking about create 1 or 2 30gb partition to act as an exact copy of the vertex drive, the idea being, I could re-flash the drive and then re-Image it from the back up partiitions on the SATA, in the event of new firmware or other goodies.

Any suggestions on this procedure?

[Amozz]

So later on in the thread you quote Amozz from above, he explicitly outlines his procedure for alignment.

That procedure was to crate an partition that precise matched an partition created by the windows tools in the alignment recommendation for windows. This is *not* the way I recommend to use for Linux. But yes, it works. (Btw, forgot to say to use the t<enter> to change the partition type to an windows type. Not sure witch type is uses? Perhaps 7 - HPFS/NTFS?)

I think you could replace the first two suggestions with his outline from this entries.

http://www.ocztechnologyforum.com/fo...8&postcount=14.

This is an better way to do it yes, but I now experiments with different values for heads/sectors. At the moment I test out 8 heads and 32 sectors pr. track. If you then start the partition on cylinder 2 it will align at sector 256 (128K).

By using this method it's easy to align. 4 heads gives an alignment on s128/64KB. 8 gives s256/128KB, 16 heads s512/256KB and 32 heads s1024/512KB and so on. Just remember to start at cylinder 2, or create an mini partition on cylinder 1 (start and end) first. This way you can rest assure that all partitions on the disk are aligned, as long as you stay on cylinder boundary. All fdisk programs under linux that I have testet insists on following the cylinder boundery, and warn you if you don't.


But, if this is the best way to do it - I don't know. And I'm open for an debate on this. Pros/cons on different values for heads and sectors. I'm know there are peoples here that can answers this better then me.

[Amozz]

Do you have any suggestions for doing the flash update to 1275 from linux?

Wait for the (free)dos version. Here I have an 120 vertex on FW1199 that has started to behave strange, so it's taken out of the computer waiting for it. I was planing to wait for the TRIM FW, but I cant wait for the autumn

I was also thinking about create 1 or 2 30gb partition to act as an exact copy of the vertex drive, the idea being, I could re-flash the drive and then re-Image it from the back up partiitions on the SATA, in the event of new firmware or other goodies.

Any suggestions on this procedure?

Looks good to me. The "image" this being rsync -ax /mnt/vertexroot /mnt/rootcopypart running of an live-cd/stick.

Re-Image is ofcourse the reverse, and then
chroot /mnt/vertexroot
grub-install
update-grub


One last thing - lately I have started to make labels on all my partitions, and then have something like this in /etc/fstab:
LABEL=root / ext3 noatime,minixdf,commit=120,errors=remount-ro 0 1
LABEL=home /home ext3 noatime,minixdf,commit=120,errors=remount-ro 0 2
and
# kopt=root=LABEL=root ro init=/sbin/preinit
in /boot/grub/menu.lst (/sbin/preinit is a script that mounts /var/log as an tmpfs before the logging starts + some more.)

This makes it easyer to move disks around or replace disks. I'm no longer depeding on that root beeing /dev/sda1 and home /dev/sdb2 or anything like that, and not depended on this ID thing thats defaultes on ubuntu.

[clarknova]

I will have a 1 TB sata for /usr, as well as for a swap partition there

I'm guessing you meant that /home will be on the hdd, not /usr. /home contains all the user's files, while /usr contains mostly program data and documentation. You probably know what you're doing, but I wouldn't want a newb to come along reading your post and following it blindly, 'cause I think it would be a mistake for the average desktop user to put /home on the SSD and /usr on the hdd.

Or maybe I'm out to lunch.

[TortureTest]

I don't think I ever came across any interesting topic regarding a swap file. TortureTest mentions "Kernel swappiness" in his post. Try to do a search with this phrase in it and you'll probable find more about the topic.

The swappiness tweak is not directly related to SSDs. However, if you
have this very fast SSD, and you notice your system still doesn't feel
as snappy as you would expect in some situations, then reducing kernel
swappiness might help. If you want to read more about kernel swappiness
and its effect on system responsiveness, http://kerneltrap.org/node/3000
is an interesting source.

[Octoploid]

Another hint:

The Vertex does not identify itself as a non-rotating medium. This can be changed by running:

echo 0 > /sys/block/sdb/queue/rotational

This helps the block layer to optimize a few decisions.
(grep the kernel tree for »nonrot« for more details)