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5697
November 26th, 2012 05:00
Difference between start reclaim and start free.
Hi All,
Can someone explain the operational difference between the below commands
a) symconfigure -sid XXX -cmd "start free on tdev XXX start_cyl=0 end_cyl=last_cyl"; commit -nop
b) symconfigure -sid XXX -cmd "start reclaim on tdev XXX "; commit -nop
As per the EMC SE product guide 7.4 it says that there isn't any difference between the two commands.I have tested the same on test LUNS and found that it is true.But the question araised when i gave the commands on the Production LUN.
Please find the below output collected during the operation:
symconfigure -sid XXX -cmd "start reclaim on tdev 1438"; commit -nop
A Configuration Change operation is in progress. Please wait...
Establishing a configuration change session...............Established.
Processing symmetrix XXXXXXXXXXXXXX
Performing Access checks..................................Allowed.
Checking Device Reservations..............................Allowed.
Locking devices...........................................Locked.
Committing configuration changes..........................Started.
Committing configuration changes..........................Committed.
Terminating the configuration change session..............Done.
The configuration change session has successfully completed.
symcfg list -tdev -detail -gb -sid XXX |find "1438"
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
symcfg list -tdev -detail -gb -sid XXX -i 10|find "1438"
Dev Pool status Capacity Allocated Written
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..R 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..B 1024.0 4 1024 100 385.0 38
1438 TH3R5600FC28 F..B 1024.0 4 1024 100 385.0 38
*****Please note that no space was reclaimed
symconfigure -sid XXX -cmd "start free on tdev 1438 start_cyl=0 end_cyl=last_cyl"; commit -nop
A Configuration Change operation is in progress. Please wait...
Establishing a configuration change session...............Established.
Processing symmetrix XXXXXXXXXXXXXXXX
Performing Access checks..................................Allowed.
Checking Device Reservations..............................Allowed.
Locking devices...........................................Locked.
Committing configuration changes..........................Started.
Committing configuration changes..........................Committed.
Terminating the configuration change session..............Done.
The configuration change session has successfully completed.
symcfg list -tdev -detail -gb -sid XXX -i 10|find "1438"
Dev Pool status Capacity Allocated Written
1438 TH3R5600FC28 F..D 1024.0 4 1019 100 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 1001 98 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 992 97 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 991 97 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 990 97 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 980 96 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 970 95 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 956 93 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 944 92 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 934 91 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 928 91 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 922 90 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 914 89 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 900 88 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 886 87 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 872 85 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 859 84 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 849 83 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 840 82 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 828 81 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 816 80 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 804 79 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 793 77 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 781 76 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 768 75 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 758 74 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 748 73 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 737 72 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 727 71 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 723 71 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 719 70 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 713 70 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 703 69 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 691 68 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 679 66 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 669 65 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 660 64 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 650 63 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 641 63 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 634 62 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 629 61 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 625 61 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 621 61 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 615 60 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 607 59 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 598 58 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 549 54 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 536 52 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 525 51 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 513 50 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 502 49 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 489 48 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 477 47 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 466 46 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 455 44 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 447 44 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 438 43 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 430 42 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 422 41 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 414 40 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 405 40 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 399 39 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 394 39 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 389 38 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 387 38 385.0 38
1438 TH3R5600FC28 F..D 1024.0 4 386 38 385.0 38
1438 TH3R5600FC28 F..B 1024.0 4 385 38 385.0 38
1438 TH3R5600FC28 F..B 1024.0 4 385 38 385.0 38
The space was reclaimed in accordance with the amount of data that was written using start free option but not by the reclaim.
Thanks,
Nag
Sam Claret
86 Posts
1
November 26th, 2012 06:00
You are correct in that the commands are the same.
When doing a space reclaim the system looks for blocks of 'zero data' that are 12 tracks in size.
If even 1 bit in that 12 tracks is non zero then that block cannot be reclaimed.
Thank you
Sam Claret TSE3
Global Technical Support – SSG Windows
arjunsingh1
32 Posts
0
November 26th, 2012 06:00
Hello,
start free on tdev [: ] start_cyl = | size = MB | GB | CYL> [type = reclaim | unwritten];
is for Solutions enabler 7.2
Starting with Solutions Enabler V7.3, two new commands, start reclaim and stop
reclaim are introduced to manage reclaiming thin device tracks. The start free
and stop free commands will continue to be supported for unwritten allocations
on a range of cylinders for a device, and for stopping the free operation on a thin
device in the De-allocating state (only).
So in 7.3 onwards :
Starting free on THIN devices (for unwritten allocations):
start free on tdev < [: ] |
in DG | in SG >
start_cyl =
|
size = MB | GB | CYL>;
New command :
Starting reclaim on THIN devices:
start reclaim on tdev < [: ] |
in DG | in SG >
[allocate_type = persistent];
Thanks
Arjun.
arjunsingh1
32 Posts
0
November 26th, 2012 06:00
Also Note :
The following text is omitted from the help output when you issue the help command for 'start free' from 7.3 onwards (not part of the syntax anymore). You can see it only in 7.2 :
[type = reclaim | unwritten];
So in short , the 'start free' can be used SE 7.3 - if you want to reclaim a part of the device. You need to mention the start cyl and end cyl.
the 'start reclaim' - if you want to reclaim the entire "unwriten" tracks.
Please see page 90 of the EMC Solutions Enabler Symmetrix Array Controls CLI version 7.4
Thanks
sauravrohilla
859 Posts
0
November 26th, 2012 08:00
In short to what Arjun said, reclaim command gives you one additional option allocate_type=persistent
start reclaim on tdev <[:] | in DG
which is not available in free tdev command.
regards
Saurabh Rohilla
dynamox
11 Legend
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20.4K Posts
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87.4K Points
0
November 27th, 2012 13:00
what does "allocate_type=persistent" mean ?
sauravrohilla
859 Posts
0
November 28th, 2012 04:00
any tdev that was persistently allocated can not be reclaim using free command, reclaim command with allocate_type=persistent option reclaims that type device.
regards,
Saurabh Rohilla
Sreehari_PwC_UK
31 Posts
0
December 21st, 2012 01:00
allocate_type = persistent means that the LUN can't be reclaimed by the normal reclaim command that is issued on devices with out persistent allocation, a LUN is persistently allocated to ensure that a critical application's allocated space is not taken off from it accidentally using the "reclaim" commands.
Thanks,
SreeHari