yeah, we will make it :) maurice, i was making some raid1 new read balance, could you help me benchmark it? it's kernel 2.6.37 based, here is the code: www.spadim.com.br/raid1/ there's raid1.new.c raid1.new.h, raid1.old.c raid1.old.h the old and new kernel source code for user space we can now make this: /sys/block/mdXXX/md/read_balance_mode /sys/block/mdXXX/md/read_balance_stripe_shift /sys/block/mdXXX/md/read_balance_config at read_balance_mode we have now 4 modes: near_head (default, working without problems, very good for hd only, ssd should other mode) round_robin (normal round robin, with per mirror counter (can make round_robin) after some reads, very good for ssd only array) stripe (like raid0, with read_balance_stripe_shift we can shift the sector number with " >> " command and after select the disk with % raid_disks, very good for hd or ssd, a good number for shift is >=5, but not so much since this can make math formula use only the first disk) time_based (based on head positioning time + read time + i/o queue time, selecting the best disk to read, work with ssd and hd very well, current implementation don't have i/o queue time but i will study and put it to work too) all configurations for round_robin and time_based as sent to kernel by read_balance_config type cat /sys/block/mdxxx/md/read_balance_config and send per disk the parameters the first line on cat command is the parameters list, after | is read only variables, you can't change it, just read use echo "0 0 0 0 0 0 0 0 0 0"> read_balance_config to change values thanks =] 2011/2/8 maurice <mhilarius@xxxxxxxxx>: > On 2/8/2011 1:50 PM, Roberto Spadim wrote: >> >> =] now the right answer :) >> question: maybe in future... could we make trim compatible with md? >> > I hope that future is "real soon now" > MLC SSD is now starting to appear in the "Enterprise space. > Companies like Pliant have released products for that. > Typical SAN RAID controllers have specific performance limits which can be > saturated with a not very large number of SSDs. > To get higher IOs we need a more powerful RAID engine > A typical 48 core, 128GB RAM box using AMD CPUs and 4 SAS HBAs to disk JBD > cases can be a ridiculously power RAID engine for a > reasonable cost ( at least reasonable compered to NetApp, EMC, Hitachi SANs, > etc) with a large number of devices. > > BUT: To use SSDs in the design we need mdadm to be more SSD friendly. > > > -- > Cheers, > Maurice Hilarius > eMail: /mhilarius@xxxxxxxxx/ > -- > 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
