Difference between revisions of "Talk:Solid State Drives"

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(What about F2FS?: Response regarding not providing information about F2FS)
m (Using discard option to mount root directory on xfs file system is no use: unsigned)
 
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== DONT USE NOOP ==
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== Don't use noop ==
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The noop scheduler will perform slow but as a result it will greatly frees up CPU cycles. This in the real world will not increase the speed of your read/writes compared to CFS but instead consume less CPU resources. You can benchmark the deadline scheduler which MAY increase performance in some circumstances. By real world benchmarks, I mean anything but hdparm. {{unsigned|22:38, 21 December 2011‎|Tama00}}
  
The noop scheduler will perform slow but as a result it will greatly frees up CPU cycles. This in the real world will not increase the speed of your read/writes compared to CFS but instead consume less CPU resources. You can benchmark the deadline scheduler which MAY increase performance in some circumstances. By real world benchmarks, I mean anything but hdparm.
 
 
:Interesting assertion... do you have any data or a source to back it up?
 
:Interesting assertion... do you have any data or a source to back it up?
 
:[[User:Graysky|Graysky]] 17:20, 21 December 2011 (EST)
 
:[[User:Graysky|Graysky]] 17:20, 21 December 2011 (EST)
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::[[User:raymondcal|raymondcal]] 2012, may 29
 
::[[User:raymondcal|raymondcal]] 2012, may 29
  
:::''CFQ has some optimizations for SSDs and if it detects a non-rotational
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:::''CFQ has some optimizations for SSDs and if it detects a non-rotational media which can support higher queue depth (multiple requests at in flight at a time), then it cuts down on idling of individual queues and all the queues move to sync-noidle tree and only tree idle remains. This tree idling provides isolation with buffered write queues on async tree.''
:::media which can support higher queue depth (multiple requests at in
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:::flight at a time), then it cuts down on idling of individual queues and
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:::all the queues move to sync-noidle tree and only tree idle remains. This
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:::tree idling provides isolation with buffered write queues on async tree.''
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:::https://www.kernel.org/doc/Documentation/block/cfq-iosched.txt
 
:::https://www.kernel.org/doc/Documentation/block/cfq-iosched.txt
 
:::[[User:ushi|ushi]] 2013, November 03
 
:::[[User:ushi|ushi]] 2013, November 03
  
== Alignment ==
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::::So does anyone have any good data? My research says deadline is best and that "cfq has some optimizations" doesn't mean it's better than others.
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::::[[User:MindfulMonk|MindfulMonk]] ([[User talk:MindfulMonk|talk]]) 22:38, 5 July 2014 (UTC)
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== TRIM and RAID ==
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The wiki article within the warning in the section '''Enable continuous TRIM by mount flag''' says: A possible [http://www.spinics.net/lists/raid/msg49440.html patch] has been posted on July 19, 2015.''"
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The quoted spinics article seems to be saying that there is a serious kernel bug which impacts when SSD's are being used with linux software raid.
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Is that a confirmed kernel bug? If it is then shouldnt the wiki point this out?
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{{unsigned|27 September 2015 08:26|Sja1440}}
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:The bug was manifested for particular brand SSD bios only, which were blacklisted. Since TRIM is a standard and other brands work fine, this issue was not regarded a kernel bug to my knowledge. Nonetheless, they may (have) merge(d) the patch to work-around the bios bugs. If someone has a related bug report where it is tracked or kernel commit, it would be useful to add, I agree. -[[User:Indigo|Indigo]] ([[User talk:Indigo|talk]]) 09:23, 27 September 2015 (UTC)
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::I found [http://linux.slashdot.org/story/15/07/30/1814200/samsung-finds-fixes-bug-in-linux-trim-code this] Slashdot discussion (linked with [https://wiki.archlinux.org/index.php?title=Solid_State_Drives&type=revision&diff=402057&oldid=400007]) where there's a link to a kernel commit, although they're talking of a bug in the firmware too, and in fact the devices seem to be still [https://github.com/torvalds/linux/blob/master/drivers/ata/libata-core.c#L4220 blacklisted]. — [[User:Kynikos|Kynikos]] ([[User talk:Kynikos|talk]]) 02:26, 28 September 2015 (UTC)
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: Samsung's patch about data corruption are now merged, but full blacklist still here in Linux 4.5 https://github.com/torvalds/linux/blob/v4.5/drivers/ata/libata-core.c#L4223 for a lot of SDD brand, in particular all the popular Samsung 8 series (840|850 EVO|PRO). I still cannot find any information about the source issue and when it will be whitelisted. The article should warn user that all those SSD models should be avoided until a solution. Note that also --[[User:Nomorsad|Nomorsad]] ([[User talk:Nomorsad|talk]]) 11:03, 26 March 2016 (UTC)
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:: The article does warn; I have updated with your 4.5 link, thanks for follow-up. They added one more drive model to the blacklist since then.[https://wiki.archlinux.org/index.php?title=Solid_State_Drives&type=revision&diff=427892&oldid=424520] --[[User:Indigo|Indigo]] ([[User talk:Indigo|talk]]) 11:19, 26 March 2016 (UTC)
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== Choice of filesystem ==
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I will expand on the prior [https://wiki.archlinux.org/index.php?title=Solid_State_Drives&diff=next&oldid=411925 accuracy flag] here:
  
The information about alignment is missing
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The two sentences in the introduction of [[SSD#Choice of filesystem]] are ambiguous at best, "''This section describes optimized filesystems to use on a SSD.''" followed by "''It's still possible/required to use other filesystems, e.g. FAT32 for the EFI System Partition.''" may be understood as either "FAT32 is not optimized for SSD" or "the list below is not complete" or simply "using filesystems not listed below will still work".
[[User:Juen|Juen]] ([[User talk:Juen|talk]]) 06:28, 20 January 2013 (UTC)
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The second part of the accuracy dispute is more serious, it does not describe "optimized" filesystems, but filesystems "with support for SSD/wear-leveling features". It's not necessarily a bad thing to describe only "support", it may very well be the only sensible way, but it shouldn't claim otherwise.
  
Both {f,g}disk handle alignment automatically.  Why introduce erroneous info to the already bloated article?
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-- [[User:Lahwaacz|Lahwaacz]] ([[User talk:Lahwaacz|talk]]) 19:29, 13 December 2015 (UTC)
[[User:Graysky|Graysky]] ([[User talk:Graysky|talk]]) 13:48, 20 January 2013 (UTC)
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== What about F2FS? ==
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== Using discard option to mount root directory on xfs file system is no use ==
  
In the [https://wiki.archlinux.org/index.php/Solid_State_Drives#Choice_of_Filesystem Choice of Filesystem] section, isn't it time to include some information about [http://en.wikipedia.org/wiki/F2FS F2FS] since [http://hothardware.com/News/Linux-Kernel-38-Released-Includes-F2Fs-Files-System-for-Solid-State-Storage/ Linux Kernel 3.8 Includes F2FS File System for Solid State Storage]
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After I modified /etc/fstab and add the discard option to the / entry, I reboot my laptop. But when I use mount command to check the options about the file system how to be mounted, there is no discard option in the / entry. and the other directory such as /home and /boot are mounted with discard option correctly.
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I have tried to remount root directory with discard option, but there is no use.
  
:Perhaps, but after examining this [http://www.phoronix.com/scan.php?page=article&item=linux_f2fs_benchmarks&num=1 performance comparison by Phoronix], you have to ask if the (slight) performance advantage of F2FS outweighs the stability and support of ext4.
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{{unsigned|03:03, 27 May 2016‎|Cfunc}}
:Might the article become more bloated and confusing for little or no real advantage ?  [[User:Kal|Kal]] ([[User talk:Kal|talk]]) 17:12, 19 August 2013 (UTC)
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::See [[ArchWiki:About#Comprehensive]]. Information relevant to Arch Linux should be provided so that the end user to make the decision. As I understand it, Arch Wiki is meant to be ''descriptive'' not ''prescriptive.'' -- [[User:AdamT|AdamT]] ([[User_talk:AdamT|Talk]]) 20:26, 17 November 2013 (UTC)
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Latest revision as of 09:02, 27 May 2016

Don't use noop

The noop scheduler will perform slow but as a result it will greatly frees up CPU cycles. This in the real world will not increase the speed of your read/writes compared to CFS but instead consume less CPU resources. You can benchmark the deadline scheduler which MAY increase performance in some circumstances. By real world benchmarks, I mean anything but hdparm. —This unsigned comment is by Tama00 (talk) 22:38, 21 December 2011‎. Please sign your posts with ~~~~!

Interesting assertion... do you have any data or a source to back it up?
Graysky 17:20, 21 December 2011 (EST)
It seems that the cfq scheduler already knows what to do when SSD is detected, so there is no use to change it.
raymondcal 2012, may 29
CFQ has some optimizations for SSDs and if it detects a non-rotational media which can support higher queue depth (multiple requests at in flight at a time), then it cuts down on idling of individual queues and all the queues move to sync-noidle tree and only tree idle remains. This tree idling provides isolation with buffered write queues on async tree.
https://www.kernel.org/doc/Documentation/block/cfq-iosched.txt
ushi 2013, November 03
So does anyone have any good data? My research says deadline is best and that "cfq has some optimizations" doesn't mean it's better than others.
MindfulMonk (talk) 22:38, 5 July 2014 (UTC)

TRIM and RAID

The wiki article within the warning in the section Enable continuous TRIM by mount flag says: A possible patch has been posted on July 19, 2015."

The quoted spinics article seems to be saying that there is a serious kernel bug which impacts when SSD's are being used with linux software raid.

Is that a confirmed kernel bug? If it is then shouldnt the wiki point this out? —This unsigned comment is by Sja1440 (talk) 27 September 2015 08:26. Please sign your posts with ~~~~!

The bug was manifested for particular brand SSD bios only, which were blacklisted. Since TRIM is a standard and other brands work fine, this issue was not regarded a kernel bug to my knowledge. Nonetheless, they may (have) merge(d) the patch to work-around the bios bugs. If someone has a related bug report where it is tracked or kernel commit, it would be useful to add, I agree. -Indigo (talk) 09:23, 27 September 2015 (UTC)
I found this Slashdot discussion (linked with [1]) where there's a link to a kernel commit, although they're talking of a bug in the firmware too, and in fact the devices seem to be still blacklisted. — Kynikos (talk) 02:26, 28 September 2015 (UTC)
Samsung's patch about data corruption are now merged, but full blacklist still here in Linux 4.5 https://github.com/torvalds/linux/blob/v4.5/drivers/ata/libata-core.c#L4223 for a lot of SDD brand, in particular all the popular Samsung 8 series (840|850 EVO|PRO). I still cannot find any information about the source issue and when it will be whitelisted. The article should warn user that all those SSD models should be avoided until a solution. Note that also --Nomorsad (talk) 11:03, 26 March 2016 (UTC)
The article does warn; I have updated with your 4.5 link, thanks for follow-up. They added one more drive model to the blacklist since then.[2] --Indigo (talk) 11:19, 26 March 2016 (UTC)

Choice of filesystem

I will expand on the prior accuracy flag here:

The two sentences in the introduction of SSD#Choice of filesystem are ambiguous at best, "This section describes optimized filesystems to use on a SSD." followed by "It's still possible/required to use other filesystems, e.g. FAT32 for the EFI System Partition." may be understood as either "FAT32 is not optimized for SSD" or "the list below is not complete" or simply "using filesystems not listed below will still work".

The second part of the accuracy dispute is more serious, it does not describe "optimized" filesystems, but filesystems "with support for SSD/wear-leveling features". It's not necessarily a bad thing to describe only "support", it may very well be the only sensible way, but it shouldn't claim otherwise.

-- Lahwaacz (talk) 19:29, 13 December 2015 (UTC)

Using discard option to mount root directory on xfs file system is no use

After I modified /etc/fstab and add the discard option to the / entry, I reboot my laptop. But when I use mount command to check the options about the file system how to be mounted, there is no discard option in the / entry. and the other directory such as /home and /boot are mounted with discard option correctly. I have tried to remount root directory with discard option, but there is no use.

—This unsigned comment is by Cfunc (talk) 03:03, 27 May 2016‎. Please sign your posts with ~~~~!