77MB/sec is good. If you're wondering where the bottleneck is to going faster, start with" iostat -dMmxzn 10" . Ignore the first set of data it's historical. For 2nd and following, look to how many reads and writes / second and the number of megabytes read/written. That gives you an idea of how much data is transferred at the device level (should be more than your 77MB/sec.) per disk. As for capacity look to the %b column which tells you the percentage of time the disk is busy. While you could consider whether it's busy because it can't handle more requests/second but the channel could handle more data per request, that won't have a 10 second duration. I would expect a modern 15K RPM SCSI-3 disk, over Infiniband or Fiber Channel, to handle over 2K IOP/second. You also would hope to transfer a full buffer on every IOP -- certainly in excess of 64MB. Sounds like either your disks have large buffer or you are using LUNs from an array which has a separate RAM buffer in front of all the drives (in which case you would probably not be doing any kind of RAID within one array...a mirror across two arrays is another matter but to mirror 2 LUNs from same array...).
From: [email protected] [mailto:[email protected]] On Behalf Of Mark Schipper Sent: Friday, April 26, 2013 3:48 AM To: Boddula, Shashi Kanth (HP-SW-LIT); [email protected] Subject: Re: [Veritas-vx] Creating mirror volume takes lot of times If I did my math right (which is debatable at ~1am) your sync rate is just over 77MB/sec. That is actually quite good. 2TB is a lot of one's and zero's to sync. I would be very happy with that time. From: [email protected] [mailto:[email protected]] On Behalf Of Boddula, Shashi Kanth (HP-SW-LIT) Sent: Friday, April 26, 2013 12:12 AM To: [email protected] Subject: [Veritas-vx] Creating mirror volume takes lot of times VxVM 5.0.3. Creating a 2 TB mirror volume taking almost a quarter day (vxassist -g dg make vol 2000g layout=mirror nmirror=2 mirror=enclr ....) with drl and fastrsync options. #vxtask Work time: 7 hours, 8 minutes, 12 seconds (26:54 remaining) Just want to check whether it is common behavior to take this much time to create mirror volumes or this refers to any bug or upgrading to 5.1 is a better option. Thanks & Regards, Shashi Kanth
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