[opensuse] 11.2 + SSD: Alignment, Trim
Greetings list, I have a couple of SSD's on order and was wondering about a few points, perhaps someone in the know can help me out. I will be installing 11.2 from scratch, will 11.2 installer/disk tools properly align my Ext4 partitions to the SSD erase block size or should I manually create the partitions before I install so that I can be sure this is done? What would be the recommended method of invoking the drives Trim functionality? Is there Trim support in Factory/KOTD kernels or should I just schedule a nightly wiper.sh run? Cheers, Graham -- “What can be asserted without proof can be dismissed without proof.” - Christopher Hitchens -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Sun, May 9, 2010 at 6:26 AM, Graham Anderson
Greetings list,
I have a couple of SSD's on order and was wondering about a few points, perhaps someone in the know can help me out.
I will be installing 11.2 from scratch, will 11.2 installer/disk tools properly align my Ext4 partitions to the SSD erase block size or should I manually create the partitions before I install so that I can be sure this is done?
11.2 has no automated features for partition alignment. Factory currently does, but I've seen no reports of anyone actually testing it. You might be able to pull a recent parted from OBS and get it working with 11.2
What would be the recommended method of invoking the drives Trim functionality? Is there Trim support in Factory/KOTD kernels or should I just schedule a nightly wiper.sh run?
Even 11.2 has kernel trim support and 11.3 definitely will as well. BUT, the current kernel trim support was developed prior to real hardware being available to test with. AIUI, the current kernel support even in KOTD with real hardware reduces performance instead of increasing it, so it is a very poor solution for current generation SSDs. (New high performance SSDs may come along that make the current solution acceptable.) So wiper.sh should likely just be called nightly. Per the wiper.sh developer (Mark Lord) he has heard rumors that the Intel SSDs are not ATA-8 compliant and therefore wiper.sh (hdparm) will not work with them. Apparently he doesn't have a sample unit to test with. Even if hdparm is not compatible with the Intels it should not cause data loss. Just no ability to trim. HTH Greg
Cheers, Graham
-- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Sunday 09 May 2010 15:48:29 Greg Freemyer wrote:
11.2 has no automated features for partition alignment.
Factory currently does, but I've seen no reports of anyone actually testing it.
You might be able to pull a recent parted from OBS and get it working with 11.2
Good to know about Factory, I'll maybe run the factory installer first and put 11.2 on after to see how the default partitioning works out. I guess I can always fall back to fdisk and work it out manually if i hit problems.
Even 11.2 has kernel trim support and 11.3 definitely will as well.
BUT, the current kernel trim support was developed prior to real hardware being available to test with. AIUI, the current kernel support even in KOTD with real hardware reduces performance instead of increasing it, so it is a very poor solution for current generation SSDs.
To avoid performance loss, how would one ensure this was disabled or is it disabled by default?
So wiper.sh should likely just be called nightly. Per the wiper.sh developer (Mark Lord) he has heard rumors that the Intel SSDs are not ATA-8 compliant and therefore wiper.sh (hdparm) will not work with them. Apparently he doesn't have a sample unit to test with.
Oh ouch, not great news for Intel SSD owners on Linux given the performance of using the Kernel based Trim option. I didn't opt for an Intel drive due to lackluster 4k random/sequential write performance on the consumer grade drives. I plumped for a SandForce controller based unit. I felt the compressed storage technique for higher 4k random/sequential writes would suit my workload well (thrashing tons of small text files all day). You lose out a bit with a slightly larger amount of reserved space for the controller to use; but I think all consumer grade SSD's have a compromise somewhere at the moment. Thanks for the info, Graham -- “What can be asserted without proof can be dismissed without proof.” - Christopher Hitchens -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
On Sun, May 9, 2010 at 11:22 AM, Graham Anderson
On Sunday 09 May 2010 15:48:29 Greg Freemyer wrote:
11.2 has no automated features for partition alignment.
Factory currently does, but I've seen no reports of anyone actually testing it.
You might be able to pull a recent parted from OBS and get it working with 11.2
Good to know about Factory, I'll maybe run the factory installer first and put 11.2 on after to see how the default partitioning works out. I guess I can always fall back to fdisk and work it out manually if i hit problems.
The best default is to start your partitions on 1MiB boundaries. Works perfectly for 512, 4K, 128K, etc. It is now the default for parted. Basically the only time parted won't use it is if a raid array is in use and the stripe doesn't align with 1MiB. In theory non-1MB harddrives also exist and parted is supposed to identify those and adjust the partitioning. I'm not sure those drives do or ever will exist. It seems that in the last 9 months the drive manufacturers all decided to only release products that align with 1MiB. (fyi: Vista and newer setup partitions on 1MiB boundaries.)
Even 11.2 has kernel trim support and 11.3 definitely will as well.
BUT, the current kernel trim support was developed prior to real hardware being available to test with. AIUI, the current kernel support even in KOTD with real hardware reduces performance instead of increasing it, so it is a very poor solution for current generation SSDs.
To avoid performance loss, how would one ensure this was disabled or is it disabled by default?
The kernel defaults it off. You have to "mount -o discard" if you want it. So just verify discard is not in your fstab.
So wiper.sh should likely just be called nightly. Per the wiper.sh developer (Mark Lord) he has heard rumors that the Intel SSDs are not ATA-8 compliant and therefore wiper.sh (hdparm) will not work with them. Apparently he doesn't have a sample unit to test with.
Oh ouch, not great news for Intel SSD owners on Linux given the performance of using the Kernel based Trim option.
I'm sure Mark will get hdparm fixed at some point. The issue is that the spec calls for a single trim command accepting thousands of ranges in large vector list. Thus one command can trim thousands of discrete sector ranges. The rumor Mark has heard is that Intel only supports one 512 byte block of vector info. If that's true, hdparm will need a update to identify Intel's and restrict the number of ranges he sends it per trim command. fyi: the trim command is not queue-able, so it flushes the drive command queue everytime. Thus hdparm is designed to call trim with as large a set of discard ranges as it can, thus reducing the number of discrete trim commands. Greg -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
I decided the below should be in the wiki, so I put it on my home page.
http://en.opensuse.org/User:Gregfreemyer
Hopefully someone on the factory list will volunteer to put it on a
real wiki page.
Greg
On Sun, May 9, 2010 at 9:48 AM, Greg Freemyer
On Sun, May 9, 2010 at 6:26 AM, Graham Anderson
wrote: Greetings list,
I have a couple of SSD's on order and was wondering about a few points, perhaps someone in the know can help me out.
I will be installing 11.2 from scratch, will 11.2 installer/disk tools properly align my Ext4 partitions to the SSD erase block size or should I manually create the partitions before I install so that I can be sure this is done?
11.2 has no automated features for partition alignment.
Factory currently does, but I've seen no reports of anyone actually testing it.
You might be able to pull a recent parted from OBS and get it working with 11.2
What would be the recommended method of invoking the drives Trim functionality? Is there Trim support in Factory/KOTD kernels or should I just schedule a nightly wiper.sh run?
Even 11.2 has kernel trim support and 11.3 definitely will as well.
BUT, the current kernel trim support was developed prior to real hardware being available to test with. AIUI, the current kernel support even in KOTD with real hardware reduces performance instead of increasing it, so it is a very poor solution for current generation SSDs. (New high performance SSDs may come along that make the current solution acceptable.)
So wiper.sh should likely just be called nightly. Per the wiper.sh developer (Mark Lord) he has heard rumors that the Intel SSDs are not ATA-8 compliant and therefore wiper.sh (hdparm) will not work with them. Apparently he doesn't have a sample unit to test with.
Even if hdparm is not compatible with the Intels it should not cause data loss. Just no ability to trim.
HTH Greg
Cheers, Graham
-- Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer CNN/TruTV Aired Forensic Imaging Demo - http://insession.blogs.cnn.com/2010/03/23/how-computer-evidence-gets-retriev... The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org
participants (2)
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Graham Anderson
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Greg Freemyer