Not very familiar with either but is it possible to disable replication for the volume you are formatting while it is being formatted and then re-enable? If the bottleneck is in the replication, then speeding up the dasdfmt code may not be of much help.
-----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Marcy Cortes Sent: Tuesday, March 04, 2014 10:36 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: dasdfmt slowness It is in a way. It is way worse under PPRC replication. XRC replication probably isn't helping either. We do both. Marcy -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Aria Bamdad Sent: Tuesday, March 04, 2014 7:19 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: [LINUX-390] dasdfmt slowness Marcy, On my SLES 11-SP3 system, I can format a 65K cyl disk in a little over 12 minutes without PAV, etc. which is quite different from your 42 minutes number. Maybe this is somehow hardware related? systest:~ # time dasdfmt -f /dev/dasdk Please enter the blocksize of the formatting [4096]: Drive Geometry: 64550 Cylinders * 15 Heads = 968250 Tracks I am going to format the device /dev/dasdk in the following way: Device number of device : 0xfff Labelling device : yes Disk label : VOL1 Disk identifier : 0X0FFF Extent start (trk no) : 0 Extent end (trk no) : 968249 Compatible Disk Layout : yes Blocksize : 4096 --->> ATTENTION! <<--- All data of that device will be lost. Type "yes" to continue, no will leave the disk untouched: yes Formatting the device. This may take a while (get yourself a coffee). Finished formatting the device. Rereading the partition table... ok real 12m39.650s user 0m0.051s sys 0m2.618s webml:~ # uname -a Linux systest 3.0.93-0.8-default #1 SMP Tue Aug 27 08:44:18 UTC 2013 (70ed288) s390x s390x s390x GNU/Linux -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Marcy Cortes Sent: Tuesday, March 04, 2014 10:03 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: dasdfmt slowness I did discover that I can do a whole bunch of them in parallel, getting the i/o rates 4000k/sec or so seemingly without any effect to anyone else. When it’s a 1TB LVM, I don't want to split them any further, but waiting an hour or two so isn't as bad as doing them one at a time. Thanks for the xargs tip! Good idea! -----Original Message----- From: Linux on 390 Port [mailto:LINUX-390@VM.MARIST.EDU] On Behalf Of Pavelka, Tomas Sent: Tuesday, March 04, 2014 12:01 AM To: LINUX-390@VM.MARIST.EDU Subject: Re: [LINUX-390] dasdfmt slowness What we do to speed dasdfmt up is to split the large dasd into smaller minidisks and join them by LVM. Then the individual minidisks can be formatted in parallel. This is easy to script with xargs, which has the parameter --max-procs that lets you specify the maximum number of worker processes to spawn. Tomas ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to lists...@vm.marist.edu with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For more information on Linux on System z, visit http://wiki.linuxvm.org/
