fragmention issue with ext4: e4defrag?

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От Marc Mamin
Тема fragmention issue with ext4: e4defrag?
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Msg-id B6F6FD62F2624C4C9916AC0175D56D8828A9B485@jenmbs01.ad.intershop.net
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Ответы Re: fragmention issue with ext4: e4defrag?  (Kevin Grittner <kgrittn@ymail.com>)
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Hello,

Has anyone some experience using defragmentation tools on Linux against tablespaces ?

we are facing fragmentation problems with postgres instances having a few TB of data.
( RAID 5 )

I/O througput decreased from 300MB/s to 160.


- We first moved some schemas to separate servers.
  After that we still have  150'000 tables in 1.5 TB

- Now we are in the process of vacuuming FULL historical tables which are not written anymore.
  This seems to improve the I/O considerably

Our remaining issue is that the free space fragmentíon is still suboptimal
so that fragmention will probably start again soon.

Would it make sense to use a tool like e4defrag
(http://www.linux.org/threads/online-defragmentation.4121/)
in order to defrag the free space ?
And how safe is it to use such a tool against a running postgres instance?



many thanks,

Marc Mamin


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