SSD hard disks and AmigaOS

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SSD hard disks and AmigaOS

Postby Gregor » Sat Oct 24, 2015 3:57 pm

Is there somewehere a FAQ concerning the use of SSDs with AmigaOS 4.1? If not, here are some questions...

1. AmigaOS does not have TRIM support and probably never will as discussed here earlier. Thus, is there any sense of using SSDs in their current state with AmigaOS...?

2. How to choose a drive which would work best with AmigaOS? Some manufacturers claim that their internal 'cleaning' processes are adequate for an OS without TRIM support. E.g. Crucial has in their SSDs so called 'Active Garbage Collection', but has anyone tested this with AmigaOS? Does it really work...?

3. What is the correct way to prep and partition a SSD (with HDToolbox)? If I have understood right, the borders of partitions should be placed in a certain way... Does HDToolbox do that automatically with SSDs?

4. What filesystem(s) should be used with SSDs?

5. Something else to take into consideration... ?
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Re: SSD hard disks and AmigaOS

Postby thomasrapp » Sat Oct 24, 2015 7:58 pm

Gregor wrote:Some manufacturers claim that their internal 'cleaning' processes are adequate for an OS without TRIM support. E.g. Crucial has in their SSDs so called 'Active Garbage Collection', but has anyone tested this with AmigaOS? Does it really work...?


Automatic trim can only work in conjunction with wear-levelling. And wear-levelling only works if there is enough unused space on the disk. This means:
- leave some space without partitions
- never format a partition. Only use quick-format


What is the correct way to prep and partition a SSD (with HDToolbox)? If I have understood right, the borders of partitions should be placed in a certain way...


Change geometry so that one cylinder is 1 MB (2048 blocks). Then partitions will be aligned automatically. Do not use 1008 or 2016 blocks per cylinder.


What filesystem(s) should be used with SSDs?


Use a file system which supports different block sizes and set block size to 4096 or 8192.
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Re: SSD hard disks and AmigaOS

Postby Gregor » Mon Oct 26, 2015 3:50 pm

thomasrapp wrote:Automatic trim can only work in conjunction with wear-levelling. And wear-levelling only works if there is enough unused space on the disk. This means:
- leave some space without partitions
- never format a partition. Only use quick-format

Change geometry so that one cylinder is 1 MB (2048 blocks). Then partitions will be aligned automatically. Do not use 1008 or 2016 blocks per cylinder.

Use a file system which supports different block sizes and set block size to 4096 or 8192.


Thank you for your advice!-) Maybe this information could also be added into the AmigaOS wiki? There was hardly anything about using SSDs yet... They are becoming more and more common but it is not easy for ordinary end users to figure out all these details, especially how to adjust the geometry.
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Re: SSD hard disks and AmigaOS

Postby tonyw » Mon Oct 26, 2015 11:55 pm

I have two Kingston SSDs, a 120 GB and a 340 GB. Both identify themselves as having 512-byte blocks, so I can't use them in a native 4096-byte manner.

Perhaps the device drivers have to be enhanced to enable "native" operation? Is it disabled by default and must be enabled by the driver?

BTW, a user should not *have* to do anything especial to use a device that plugs into a standard SATA port and uses a standard device driver. It's a hardware issue and should be handled at that level.
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Re: SSD hard disks and AmigaOS

Postby HKvalhe » Thu Nov 26, 2015 12:57 pm

tonyw wrote:I have two Kingston SSDs, a 120 GB and a 340 GB. Both identify themselves as having 512-byte blocks, so I can't use them in a native 4096-byte manner.

Perhaps the device drivers have to be enhanced to enable "native" operation? Is it disabled by default and must be enabled by the driver?

BTW, a user should not *have* to do anything especial to use a device that plugs into a standard SATA port and uses a standard device driver. It's a hardware issue and should be handled at that level.


It would be great if it was possible to use the maximum capacity of speed and quality of SSD in AmigaOS. It would certainly help a lot if such could be done...
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Re: SSD hard disks and AmigaOS

Postby Srtest » Fri Dec 04, 2015 12:23 am

thomasrapp wrote:
Gregor wrote:Some manufacturers claim that their internal 'cleaning' processes are adequate for an OS without TRIM support. E.g. Crucial has in their SSDs so called 'Active Garbage Collection', but has anyone tested this with AmigaOS? Does it really work...?


Automatic trim can only work in conjunction with wear-levelling. And wear-levelling only works if there is enough unused space on the disk. This means:
- leave some space without partitions
- never format a partition. Only use quick-format


What is the correct way to prep and partition a SSD (with HDToolbox)? If I have understood right, the borders of partitions should be placed in a certain way...


Change geometry so that one cylinder is 1 MB (2048 blocks). Then partitions will be aligned automatically. Do not use 1008 or 2016 blocks per cylinder.


What filesystem(s) should be used with SSDs?


Use a file system which supports different block sizes and set block size to 4096 or 8192.


Gparted:
"The Cylinder/Head/Sector values reported by modern disk devices no longer have a direct physical relationship to the data stored on the disk device. Hence it is no longer valid to use this alignment setting to achieve enhanced performance."
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Re: SSD hard disks and AmigaOS

Postby thomasrapp » Sat Dec 05, 2015 12:35 am

Srtest wrote:Gparted:
"The Cylinder/Head/Sector values reported by modern disk devices no longer have a direct physical relationship to the data stored on the disk device. Hence it is no longer valid to use this alignment setting to achieve enhanced performance."


Exactly. That's why you have to edit the geometry manually. Using the values reported by devices, you still get this 63/16 thing. To get proper performance from an SSD you should enter values which ensure megabyte alignment.
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Re: SSD hard disks and AmigaOS

Postby tonyw » Sat Dec 05, 2015 8:54 am

Why megabyte?
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Re: SSD hard disks and AmigaOS

Postby gazelle » Sat Dec 05, 2015 12:29 pm

An SSD has its own way of writing data. Normaly an SSD doesn't only write one Block to the disk. It does some merging (to 256 or 512KiB I think).

A partition should not cross this "merged" block to get better performance. If you set the alignment to 1MiB you can be sure of that. It could be lower but you would need to know the details of your SSD, so the general rule is 1MiB.

Or that's how I understand it.
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Re: SSD hard disks and AmigaOS

Postby Srtest » Sat Dec 05, 2015 7:14 pm

"it isn't immediately clear to me exactly what an SSD should report its topology as given the current interfaces."
https://lwn.net/Articles/428584/
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