[OpenIndiana-discuss] ashift 13?

[Jim Klimov]

7 апреля 2015 г. 20:25:45 CEST, Jason Matthews <jason at broken.net> пишет:
>
>
>On 4/7/2015 11:07 AM, Jim Klimov wrote:
>>
>> As for inflation - whenever you have smaller zfs allocations, such as
>those "tails" from blocks sized not power of 2 thanks to compression,
>they become a complete minimal "recordsize" block such as 4k or 8k as
>native to your drives, with trailing zero-padding. Some metadata blocks
>may also fall into this category, though for larger files these are
>clustered at 16kb(?) chunks. You also have less uberblocks in the
>fixed-size ring buffer of zpool labels.
>
>I am not sure tails justifies the inflation. I can accept some
>increased 
>utilization from tails but this is totally out of line.
>
>Here is a 512b system of a database master.
>root at shard035a:/home/postgres/data/base/16414# du -hs .
>  203G   .
>root at shard035a:/home/postgres/data/base/16414# ls -l |wc -l
>     4109
>
>203GB and 4109 files.
>
>Here is the slave that I built from the master yesterday. They should
>be 
>nearly identical.
>
>root at shard035b:/home/postgres/data/base/16414# du -hs .
>  474G   .
>root at shard035b:/home/postgres/data/base/16414# ls -l |wc -l
>     4081
>
>My feeling is there are not enough tails in 4100 files to consume 271GB
>
>of storage. I dont understand what is going on just yet.
>
>j.
>
>
>
>
>> On the upside, if your ssd does compression, these zeroes will in
>effect likely count toward wear-leveling reserves ;) With hdds this is
>more of a lost space as compared to 512-byte sectored disks. However
>this just become similar to usage on other systems (ext3, ntfs)
>typically with 4k clusters anyway. So we're told to not worry and love
>the a-bomb ;)
>>
>
>
>
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Also, how did you build the slave? Binary file copy? Zfs send? Import from sql/dump files?

Are compression/copies/recordsize etc. settings the same on two dataset contents?

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