Re: 177 SSD to 775 SSD Disk Swap, including load source

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- Larry "DrFranken" Bolhuis

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On 3/15/2015 1:56 PM, Steinmetz, Paul wrote:
<snip>

1) When starting RAID-5 with hot spare, I lost 2 units to hot spare, originally I was informed only 1 would be needed, not sure why?
Documentation states you only need 1 hot spare per IOA.
Not sure if I can correct this, possibly remove the 2nd hot spare.

You said it, "Per IOA" and since you have two 5913s... :-)

Yes you could remove the second one but I would recommend against doing that.

2) When adding disks, if empty disk slots available,, use 8. Device Concurrent Maintenance and avoid IPL.
IPL marks drives as "dirty" and forces an initialize during prep. 140 minutes for a single 775 SSD.
Last week I had to cancel option 9, disk to disk copy of load source because of this added prep time.

Excellent point. So long as the RAID card knows that it has written the drive full of zeros (initialized it) you save that time so doing that in advance of copy or start RAID takes that time off the critical path.

3) "Prep" or "Initialize" times.

According to IBM, when Option 9, copy disk unit data, requests the destination disk.
IBM sends a command to the disk.
If it comes back as a "clean" disk, then initialize is NOT done.
If it comes back as a "dirty" disk, then IBM issues the command to format the drive.
Each drive manufacture may do formatting differently.
Currently, there is no known method to determine if a drive is "clean" or "dirty"

This also applies when "Adding to ASP"

So it's not IBM's code, but the various disk manufactures format procedures and if a disk is "clean" or "dirty" that determine the time needed for "load source disk to disk copy" and/or "add to asp".

Hmmm. That's interesting, seems like IBM could tell them how to initialize prior to shipping!

My other 5 drives must have been "clean" only 1 minute to "Add to ASP"
When drives where smaller, 4, 8, 17, 35 etc, these times were much smaller.

IBM is working to reduce these "Prep" times in future release as these times keep increasing as drives get larger.

4) When moving the load source, IPL to DST,
A) Add new drives concurrent.
B) Start RAID-5 with hot spare, 1 minute
C) Load source move - option 9, disk to disk copy.
D) Load source "prep" only 1 minute, "clean" drive and new parity set.
E) Load source copy from old 177 SSD to new 775 SSD, 40 minutes.
F) Delay adding other drives to ASP, do after IPL using SST, not DST. 3 to 4 hours.

5) After all new disks are added
STRASPBAL TYPE(*CAPACITY) TIMLMT(*NOMAX) PRIORITY(*MEDIUM)

Thank You
_____
Paul Steinmetz
IBM i Systems Administrator

Pencor Services, Inc.
462 Delaware Ave
Palmerton Pa 18071

610-826-9117 work
610-826-9188 fax
610-349-0913 cell
610-377-6012 home

psteinmetz@xxxxxxxxxx<mailto:psteinmetz@xxxxxxxxxx>
http://www.pencor.com/







Thank You
_____
Paul Steinmetz
IBM i Systems Administrator

Pencor Services, Inc.
462 Delaware Ave
Palmerton Pa 18071

610-826-9117 work
610-826-9188 fax
610-349-0913 cell
610-377-6012 home

psteinmetz@xxxxxxxxxx<mailto:psteinmetz@xxxxxxxxxx>
http://www.pencor.com/