yes i found it in my /sys filesystem, a rotational information 0 for hd 1 for ssd i write a long time ago a more interesting algorithm but complex... a minimal time algorithm, it should have information about head position time, read time (per bit, per byte, per units....) and calculate the time to make a read in each disk considering that it could be reading (time to stop read current requestion) and after this get the smallest time -> the best read performace if we use only ssd disk today implementation isn´t good, if we use hdd maybe a good (if we don´t use 7200rpm + 10000rpm + 15000rpm disks), if we use a mixed ssd+hdd it will not work very good too... this should be a per disk optimization (minimal time to read) a round robin is a good feature (for ssd only) but a mixed array should allow minimal time algorithm any idea how to implement a round robin and a algorithm (per raid device) selection using sysfs? there´s a patch but i didn´t found information about how to patch the kernel with it can anyone help me? thanks 2011/1/18 Mathias Burén <mathias.buren@xxxxxxxxx>: > 2011/1/18 Keld Jørn Simonsen <keld@xxxxxxxxxx>: >> On Tue, Jan 18, 2011 at 12:00:49PM -0200, Roberto Spadim wrote: >>> like this patch (a long time ago) >>> http://www.spinics.net/lists/raid/msg30003.html >>> >>> >>> 2011/1/18 Roberto Spadim <roberto@xxxxxxxxxxxxx>: >>> > hi guys, could we implement a load_balance read algorithm for SSD? >>> > nearest head isn't as fast as round robin for ssd. >>> > i'm talking about raid1 (raid10 too) >>> > what's my problem? >>> > as i can see, raid0 is faster than raid1 >>> > for example: >>> > two disks raid0 is faster than >>> > two disks raid1. >>> > >>> > why? >>> > nearest head >>> > instead of a balanced read algorithm (like raid0) the nearest head >>> > make raid1 use only one disk for searchs where we could use two disks >>> > (like raid0) >>> > >>> > could we implement a round robin for ssd? and make raid1 as fast as >>> > raid0 for ssd? >>> > i didn't tested the raid10 algorithm yet. >>> > thanks a lot. >> >> This should only be in use for SSDs. For disks it would be a waste of IO >> bandwidth. How do we detect whether it is a SSSD. >> Another way to accomplish an improvement os to use the offset layout of >> raid10. >> >> best regards >> Keld >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid" in >> the body of a message to majordomo@xxxxxxxxxxxxxxx >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> > > Hi, > > There is a way to check if the device is an SSD or not; the rotational > queue flag in sysfs. See > http://amailbox.org/mailarchive/git-commits-head/2009/1/30/4859834/thread > . > > // Mathias > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
