Manoj Nayak writes:
> Roch - PAE wrote:
> > Why do you want greater than 128K records.
> >
> A single-parity RAID-Z pool on thumper is created & it consists of four
> disk.Solaris 10 update 4 runs on thumper.Then zfs filesystem is created in
> the pool.1 mb data is written to a file in filesystem using write (2)
> system call.However dtrace displays too many small sized physical disk
> read
> when the same 1 mb data is read using read() system call.recordsize is
> set to 128k.
>
> What's going on here ? why so many small size block read is done ?
>
Each record becomes it's own raid-z stripe.
When you read a 128K record it will need to issue a 128K/3 I/O
to each of the 3 data disks in the 4-disk raid-z group. But
with prefetching it's possible that the I/O scheduler
aggregate this to a higher value. It seems this is not
happening on your setup. How large are the I/Os, if smaller
than the above, is the pool rather filled up ?
More reading :
http://blogs.sun.com/roch/entry/when_to_and_not_to (raidz)
-r
> if 0LARGE option need to be mentioned at the time of creating this file
> to tell , so that zfs use bigger block size.
>
> I think, zfs does use block size as per the following statements.
>
> ZFS files smaller than the recordsize are stored using a single
> filesystem block (FSB) of variable length in multiple of a disk sector
> (512 Bytes).
> Larger files are stored using multiple FSB, each of recordsize bytes,
> with default value of 128K.
>
> dtrace output :
>
> Event Device Device
> PathName RW Block Size Block
> No Offset Path
> sc-read . R 1052672 0 /mnt/bank0/media/CAD1/4.1
> fop_read . R 1052672 0 /mnt/bank0/media/CAD1/4.1
> disk_io sd6
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 65536
> 50816 0 <none>
> disk_io sd21
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 65536
> 50816 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 65536
> 50816 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 131072
> 47839 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 48095 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 48352 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 48523 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 48950 0 <none>
> disk_io sd48
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 49121 0 <none>
> disk_io sd6
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 131072
> 48096 0 <none>
> disk_io sd6
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 48352 0 <none>
> disk_io sd21
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 48267 0 <none>
> disk_io sd21
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 48438 0 <none>
> disk_io sd6
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 48523 0 <none>
> disk_io sd6
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 48951 0 <none>
> disk_io sd21
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 49891 0 <none>
> disk_io sd21
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 44032
> 50062 0 <none>
> disk_io sd6
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 49378 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 47668 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 47839 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 48608 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 49036 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 131072
> 49207 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 43520
> 50062 0 <none>
> disk_io sd13
> /devices/[EMAIL PROTECTED],0/pci1022,[EMAIL PROTECTED]/pci11ab,[EMAIL
> PROTECTED]/[EMAIL PROTECTED],0:a R 87552
> 49463 0 <none>
>
> Thanks
> Manoj Nayak
>
>
> > Do Check out :
> > http://blogs.sun.com/roch/entry/128k_suffice
> >
> > -r
> >
> >
> > Manoj Nayak writes:
> > > Hi All,
> > >
> > > Is it not poosible to increase zfs record size beyond 128k.I am using
> > > Solaris 10 Update 4.
> > >
> > > I get following error when I try to set zfs record size to 1024 k.
> > > zfs set recordsize=1024k md9/test
> > > cannot set property for 'md9/test': 'recordsize' must be power of 2
> > from
> > > 512 to 128k
> > >
> > > Thanks
> > > Manoj Nayak
> > > _______________________________________________
> > > zfs-discuss mailing list
> > > zfs-discuss@opensolaris.org
> > > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
> >
> >
>
> _______________________________________________
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