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Originally posted by kloczek View PostYou are talking about some OpenZFS issues.
Againa as ZFS is using modified SLAB allocator defragmentation is not needed.
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Originally posted by kloczek View PostSo what is wrong with fragmentation?
The problem is that a "block", just like with an SSD memory cell or SMR zone, is a monolithic thing and I cannot just read parts of it, while a block is also big enough that it can contain parts from multiple files.
If the data I need is split inside 400 blocks or if it is split inside 4000, or 40000 the performance changes because now I need to read more blocks to get the same data.
In my entire career using ZFS since Solaris 10 beta (~19y) I never ever had needs to defragment anything.
Try it than we can talk ..
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Originally posted by kloczek View PostJust please at least try to google for "zfs slab allocatior" then read first few links.
Slab allocation is a memory management mechanism intended for the efficient memory allocation of objects. Compared to earlier mechanisms, it reduces fragmentation caused by allocations and deallocations.
Key word REDUCES
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Originally posted by birdie View PostAnother great FS with no recovery tools whatsoever. Once you have a serious enough crash, or you delete files accidentally, say goodbye to your data. ext4 might not be modern, or fancy or may lack cool features but it's extremely reliable (every Android phone uses it - two billion devices).
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Originally posted by starshipeleven View PostNone is using Slowlaris, when everyone talks of ZFS they really mean OpenZFS now, old man.
I find it hard to believe that a core filesystem feature like that was changed only in the relatively recent past, in the proprietary ZFS fork that none uses because it's on Slowlaris.
(meta)SLAB alocatoor is core part of the ZFS from the beginning.
Look on "zdb -vvv" output and you will be able to find SLAB alocator metrics data.
Solaris was slow compare to Linux before Solaris 10 in which any possible to observe lower performance on Solaris was treated as critical bug.
Solaris 10 GA has been released 19 years ago.
If you will find today any symptom of the lower performance on Solaris compare to Linux you can open the bug report even without support contract and that report will be taken seriously.
Problem is that today Linux is quite often slower than Solaris especially on HW with high count of the CPU cores.
You would know that if you would be using Solaris at lease one time in your life.
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Originally posted by starshipeleven View Postlower (effective) IO? You know how fragmentation works?
The problem is that a "block", just like with an SSD memory cell or SMR zone, is a monolithic thing and I cannot just read parts of it, while a block is also big enough that it can contain parts from multiple files.
If the data I need is split inside 400 blocks or if it is split inside 4000, or 40000 the performance changes because now I need to read more blocks to get the same data.
ZFS additionally has dynamic allocation using (record) which is from 1Kb up to 16MB.
This is why SLAB allocator needs to be involved.
Look on slabtop command output on Linux or /proc/slabinfo content and you will be able to find that within each SLABs size of the allocation using is fixed and different.
Looks like you still don't know what SLAB allocatior is.
Not saying this is a major issue like it is for trash-grade filesystems like NTFS, just saying that having something to deal with it if it happens, that does not involve copying terbytes of data to an external drive would be nice. Because it still can happen, for some workloads.
Can you lend me a Slowlaris license? Because if the only way to test your claims is to pay Oracle for a businness license I'm not doing that, I'm too stingy.
None of the current filesystems has 1:1 relation to read IOs on VFS and block layer.
I have no idea how it is is with NTFS and NTFS is not subject here.
If you need Solaris you can use it for free.
Paid is support.
It is like this with Solaris and all OpenSolaris derivatives.
To download and use regular Solaris you don't need to pay anything.
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Originally posted by starshipeleven View Post
Slab allocation is a memory management mechanism intended for the efficient memory allocation of objects. Compared to earlier mechanisms, it reduces fragmentation caused by allocations and deallocations.
Key word REDUCES
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Originally posted by kloczek View Post(meta)SLAB alocatoor is core part of the ZFS from the beginning.
Solaris was slow
Keeping performance data secret does not give a good impression though.
If you will find today any symptom of the lower performance on Solaris compare to Linux you can open the bug report even without support contract and that report will be taken seriously.
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Originally posted by starshipeleven View Postthen why are you talking of OpenZFS as if it is so much different thant a core part can act so differently that it may have fragmentation problems?
Current sped of Solaris is unknown because it's Unbenchmarkable, aka part of the contract is that you cannot post benchmarks of it.
Keeping performance data secret does not give a good impression though.
Given that most of Solaris dev team has been disbanded years ago when it entered life support mode, I have my doubts.
Try OpenSolaris you can dot with OS whatever you want
Oracle does not care about marketing of the Solaris and each ear it generates for only oracle more and more income .. end of the story.
I don't know do you know that but after Sun was taken over by Oracle now only on Solaris kernel is working more people than during Sun time on entire Solaris distribution.
Every few months/SRUs is released batch of new features (I'm talking about only changes in kernel space).
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