SSD Partition alignment guide (n00b freindly!)?

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SSD Partition alignment guide (n00b freindly!)?

Postby JustSomeGeek » Fri Jun 22, 2012 12:55 pm

Hi folks,

Until this morning i thought i was ready to install CentOS Server on it's shiny new SSD (Samsung 830 256).

Now though, i have spent hours reading up on partition alignment and trying to find out Erase Block Size and Page Size for this SSD and work out what to do with the info if i ever find it.

For something that is apparently really important, there doesn't seem to be anything helpful out there.

The CentOS Bible itself doesn't even mention SSDs :-/

Help?
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Postby Dutch_Master » Fri Jun 22, 2012 1:01 pm

Modern SSD's come pre-aligned, so that shouldn't be an issue. Likewise, most modern OS's, especially Linux, also comes pre-aware of alignment issues on SSD's, so that also shouldn't much of a problem. Just put in the installation disk and have a go! :D
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Postby JustSomeGeek » Fri Jun 22, 2012 1:45 pm

Dutch_Master wrote:Modern SSD's come pre-aligned, so that shouldn't be an issue. Likewise, most modern OS's, especially Linux, also comes pre-aware of alignment issues on SSD's, so that also shouldn't much of a problem. Just put in the installation disk and have a go! :D


That's what i would have thought seeing as Linux is usually at the front with supporting new tech. But if you read some of this:

https://wiki.archlinux.org/index.php/Solid_State_Drives#Partition_Alignment

http://ypl.com/ssd/apds05.html

...it does make me wonder what i am supposed to believe. I really don't want to set up my server and then find i need to start again from scratch because things slow to a crawl after a few weeks/months. :-/
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Postby jonrob » Fri Jun 22, 2012 3:03 pm

Neil Bothwick has just written a piece about partition alignment in issue 160. Although I'm not 100% sure off the top of my head, I think he says that modern versions of fdisk and partitioning tools do alignment without any fuss. The only note he makes it to make sure you set partitions in terms of size, e.g. 20M or 20G instead of in sectors etc.
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Postby JustSomeGeek » Fri Jun 22, 2012 3:55 pm

jonrob wrote:Neil Bothwick has just written a piece about partition alignment in issue 160. Although I'm not 100% sure off the top of my head, I think he says that modern versions of fdisk and partitioning tools do alignment without any fuss. The only note he makes it to make sure you set partitions in terms of size, e.g. 20M or 20G instead of in sectors etc.


Thanks for that. I don't have 160 yet, but if it's out i'll have a look tonight. I'll keep to proper sized chunks too.

Seeing as trim has been supported in Linux since 2008(?), i would have thought it would be a non-issue now anyway. But being a n00b myself, i tend to err on the side of caution and ask.

Unless i hear anything else, i'll just whack the OS on it tomorrow and hope for the best! Ignorance really is bliss. :-)
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Postby nelz » Fri Jun 22, 2012 8:41 pm

Yes, later versions of fdisk align to MiB (2048 block) boundaries, but on a new system I'd use a GPT partition table and avoid not only this issue but also all the crap with primary, extended and logical partitions.
"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)
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Postby JustSomeGeek » Fri Jun 22, 2012 8:47 pm

nelz wrote:Yes, later versions of fdisk align to MiB (2048 block) boundaries, but on a new system I'd use a GPT partition table and avoid not only this issue but also all the crap with primary, extended and logical partitions.


I just read the article (thanks jonrob), and came to a similar conclusion, but to use Parted for it. Perfect timing, as i wasn't going to get the mag 'till next week normally!

Thanks guys! :-)
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Postby JustSomeGeek » Fri Jun 22, 2012 9:28 pm

Unless i mis-understood the mag article, GParted does seem to have an alignment option after all:

http://gparted.sourceforge.net/display-doc.php?name=help-manual#gparted-specify-partition-alignment

I'll try this out on a VM tonight/tomorrow, as i'm really not comfortable with my dyslexic command line skills on a new OS with new file-systems & drives, and with no pictures. If it doesn't work (how will i know?), i'll have a play with Parted.
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Postby nelz » Fri Jun 22, 2012 10:44 pm

GParted willl do the job, but I'd still go with GPT partition tables (parted offers a choice of partition table type in the one program, unlike the fdisk family).
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Postby JustSomeGeek » Sat Jun 23, 2012 7:41 pm

nelz wrote:GParted willl do the job, but I'd still go with GPT partition tables (parted offers a choice of partition table type in the one program, unlike the fdisk family).


Cheers Nelz. I've used GParted to set things up and it seems to be going well.
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Postby JustSomeGeek » Sun Jun 24, 2012 11:10 pm

I took the extra time to read up on LVM, so it's running on that now. Cheers! :-)
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