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On Thu, Sep 19, 2013 at 2:44 PM, Hinnerk van Bruinehsen |
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<h.v.bruinehsen@×××××××××.de> wrote: |
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> On Wed, Sep 18, 2013 at 09:49:40PM -0700, Grant wrote: |
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>> > I think many folks are interested in upgrading to EXT4 with RAID from |
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>> > an ordinary JBOD workstation(server); or better yet to ZFS on RAID. I wish |
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>> > one of the brighter minds amongst us would put out a skeleton |
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>> > (wiki) information page as such: |
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>> > |
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>> > http://wiki.gentoo.org/wiki/ZFS+RAID |
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>> > |
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>> > I know I have struggled with completing this sort of installation |
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>> > several time in the last 6 months. I'm sure this (proposed) wiki page |
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>> > would get lots of updates from the Gentoo user community. Surely, |
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>> > I'm not qualified to do this, or it would have already been on the |
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>> > gentoo wiki.... |
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>> > |
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>> > Much of the older X + RAID pages are deprecated, when one considers |
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>> > the changes that accompany such an installation ( Grub2, UUID, fstab, |
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>> > partitioning of drives, Kernel options, just to name a few). We're |
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>> > talking about quite a bit of deviation from the standard handbook |
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>> > installation, fraught with hidden, fatal mis-steps. |
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>> |
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>> Any important points or key concepts a ZFS newbie should remember when |
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>> installing with it for the first time? |
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>> |
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>> - Grant |
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> |
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> |
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> You should definitely determine the right value for ashift on pool creation |
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> (it controls the alignment on the medium). It's an option that you afaik can only set |
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> on filesystem creation and therefore needs a restart from scratch if you get it |
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> wrong. |
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> According to the illumos wiki it's possible to run a mixed pool (if you have |
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> drives requiring different alignments[1]) |
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> If in doubt: ask ryao (iirc given the right information he can tell you which |
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> are the right options for you if you can't deduce it yourself). |
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> Choosing the wrong alignment can cause severe performance loss (that's not |
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> a ZFS issue but happened when 4k sector drives appeared and tools like fdisk |
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> weren't aware of this). |
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> |
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> WKR |
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> Hinnerk |
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> |
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|
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Especially with SSDs. One must find out the blocksize used by his/her SSDs. |
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|
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With spinning disks, setting ashift=12 is enough since no spinning |
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disks have sectors larger than 2^12 bytes. |
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|
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With SSDs, one might have to set ashift=13 or even ashift=14. |
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|
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Rgds, |
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-- |
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FdS Pandu E Poluan |
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~ IT Optimizer ~ |
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|
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• LOPSA Member #15248 |
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• Blog : http://pepoluan.tumblr.com |
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• Linked-In : http://id.linkedin.com/in/pepoluan |
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