Stripe size: effects on RAID1 setups?

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Stripe size: effects on RAID1 setups?

Post by si-ghan-bi » Fri Nov 30, 2012 5:25 am

I formatted my two mirrored drives only with the casesensitivity and ashift parameters. I noticed yesterday that the block size is set to 128 KB in the "zfs get all" listing.
Does this mean that every time a change is needed, a new 128 KB block will be written at the end? This is not very efficient given the usual size of files, lower than 128 KB.
The choice comes from the need of storing checksums? or for performances?
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Re: Stripe size: effects on RAID1 setups?

Post by mk01 » Fri Nov 30, 2012 7:39 am

zfs is clever. that's why if filesize is below block size, only needed kB are allocated. so in general you will not waste the space with small files. on the other hand, iops could be compromised if with each small IO full 128kB are needed to be transferred through the bus making impossible of next io.
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Re: Stripe size: effects on RAID1 setups?

Post by si-ghan-bi » Fri Nov 30, 2012 7:49 am

Now is clear, thank you.
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