storage space sizing
TRANSCRIPT
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Confidential - NetApp Employees Only
Space Sizing
The Final Frontier
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2008 NetApp. All rights reserved.
Agenda
The Space Problem how much to quote Terms and Concepts
Space Guarantees
Snap Reserve
Fractional Reserve
Vol
Autogrow
and Snap Autodelete
Possible configurations Recommendations
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The Problem
Customer asks for 20TB of usable storage for a SAN.
How much storage do you configure in your quote?
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The Problem
Why is this a problem?
Snapshots!!!!!!!!!!!!!!!
Why is this a problem?
Cost
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The Problem
So, youve had the snapshot conversation with the
customer.and you configure the 20TB usable quote
with how much storage?
2x plus delta? i.e. ((2x20)+(20%)) = 44TB usable
Why?
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Terms and Concepts
Snapshots taken on a NetApp storage array are stored
in the same volume as the primary data
Snapshots taken on other vendors arrays are stored
in a separate snapshot area
On NetApp if you fill your volume with snapshot data
all writes to your LUNs stop and your host keels over
On other vendors arrays if you run out of snapshotspace the snapshot is failed
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Terms and Concepts FlexVol Guarantees
Volume
Default guarantee for any new volume
Space is reserved from the aggregate at volume creation time
This space is not available to other volumes regardless of how much isreally used
Fractional Reserve settings can only be changed using Volume
guarantees
None
No space is reserved from the aggregate at volume creation time
Space is taken from the volume as data is written
Allows multiple volumes to use available space from an aggregate
Any individual volume still is not allowed to take more space than itsspecified size
Permits thin provisioning
at the volume level
File
The same as none but allows individual LUNs
(or files) to set space
reservations to ensure they have adequate spaceStick with guarantee=Volume unless you have good reason to do otherwise
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Flexible Volume Space Management
Space Guarantees
Aggr
none
Aggr
volume file
NOTE: The blue blocks represent space not disks
Aggr
= claimed space
= unclaimed space
= full space
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Space Guarantees Set to volume
Aggr
volume
NOTE: Blocks represent space not disks
= claimed space
= unclaimed space
= full space
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Space Guarantees Set to none
none
= claimed space
= unclaimed space
= full space
NOTE: In reality, particular blocks are not claimed. The
volume is simply given a space limit, and space is filled
at random.
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Space Guarantees Set to file
Aggr
file
= claimed space
= unclaimed space
= full space
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Space Guarantees at FlexVol Creation
To specify a space guarantee at the creation of aFlexVol:
Example:
vol cr eat e sampl e_vol sampl e_aggr s f i l e si ze
10g
Step Action
1. Enter the following command:
vol cr eat e flexvol_name aggr_name s[ vol ume| f i l e| none] si ze [ k| m| g| t ]
2. Confirm settings, enter the following command:
vol opt i ons flexvol_name
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Space Guarantees Change or Update
To change the space guarantee for an existingFlexVol volume:
Example:
vol opt i ons sampl e_vol guar ant ee none
Step Action
1. Enter the following command:
vol opt i ons flexvol_name aggr_name guar ant ee[ vol ume| f i l e| none]
2. Confirm settings, enter the following command:
vol opt i ons flexvol_name
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Terms and Concepts - LUN Reservation
Determines when the space is taken out ofthe volume
At LUN creation (i.e. fully provisioned) When data is written to the LUN (i.e. thinprovisioned)
Equivalent of guarantees for LUNs
enable = volume
disable = none
Enabled by default
Only to be disabled for thin provision of LUNs
lun set reservation enable/disable
lun create o noreserve (creates a thin provisionedLUN)
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Terms and Concepts - Snap Reserve
Set at the volume level
ONTAP removes the defined percentagefrom the volume
Does not allow LUNs to be created or files to growinto the snap reserve space
Snapshot data fills this space
Traditionally set to 0 for volumes used withblock protocols, but does not have to be zeroin SAN environments.
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Snap Reserve
Volume 1 Space Reservation
20%
Snapshot Reserve
Volume 1 Space Reservation
20%
Snapshot Reserve
Snapshot Overflow
Figure 1 - DEFAULT Figure 2
Historically recommend setting Snap Reserve to
0 for block storage, but there are now reasons toreconsider this policy
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Terms and Concepts - Fractional Reserve
Set at the volume level (default is 100%), can only bealtered if space guarantee = volume, can be setbetween 0% and 100%
Allows thin provisioning of snapshot space
Independent of Snap Reserve
Determines amount of space ONTAP reserves forsnapshot data for LUNs
Space is reserved when the first snapshot is taken.Space reserved = used space in LUN(s)
Fractional Reserve Space is only used if no otherspace in the volume is available
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Fractional Reserve - Default
Example
Create the space reserved LUN
l un cr eat e s 100gb t ai x
/ vol / vol 1/ l un1Fractional Reserve = 100 %
guarantee = volume
space reservation
= enable
= 25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Fractional Reserve - Default
Example (cont.)
Fill the LUN
guarantee = volume
space reservation
= enable
=
25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Fractional Reserve Default
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Fractional Reserve - Default Example (cont.)
Take the Snapshot
snap cr eat e l un1 snap1
Space is Reservedguarantee = volume
space reservation
=
enable
= 25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Fractional Reserve LUN Not Filled
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Fractional Reserve - LUN Not Filled(cont.)
What happens if the LUN is not full whenthe snapshot is taken? Only the amount of space filled is reserved
guarantee = volume
space reservation
= enable
= 25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Fractional Reserve 25 Percent
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Fractional Reserve 25 Percent Example
Set Fractional Reservevol opt i ons vol 1 f r act i onal _r eser ve 25
Fractional Reserve = 25 %
guarantee = volume
space reservation
= enable
= 25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Fractional Reserve 25 Percent
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Fractional Reserve 25 Percent Example (cont.)
Take Snapshot
Space is reserved
guarantee = volume
space reservation
= enable
= 25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Fractional Reserve LUN Not Filled
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Fractional Reserve - LUN Not Filled(cont.)
What happens if fractional reserve is 25percent and the LUN is 50 percent full whenthe snapshot is taken? 12.5 GB are reserved
guarantee = volume
space reservation
= enable
= 25 GB
100 GB
= LUN1
= LUN1
= vol1
= reserved
=full
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Terms and Concepts - Snapshot Auto
Delete
Set on a per volume basis
Determines when (if) snapshots will be automatically deleted
Makes NetApp like competition but better
snap autodelete [on
| off
| show
| reset
| help] |
snap autodelete ...
Supported options and corresponding values:commitment
try, disrupt
trigger volume, snap_reserve, space_reserve
target_free_space
1-100
delete_order oldest_first, newest_first
defer_delete scheduled, user_created, prefix, none
prefix
Snapshots locked by clones, cifs or restores will not be deleted
change planned for 7.3Confidential - NetApp Employees Only
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Terms and Concepts - Volume Autosize
Set on a per volume basis
Determines if a volume should grow when nearly full
Possible settings
ON-
Maximum size (default 120% of initial size)
-
Increment size (default 5% of original size)
OFF
vol autosize [-m [k|m|g|t]][-i [k|m|g|t]][ on | off | reset ]
Try_first option determines whether auto_grow or auto_delete isattempted first
The possible try_first
values are:
snap_delete
volume_growe.g. vol options try_first snap_deleteConfidential - NetApp Employees Only
S M D f l
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Space Management Default
Configuration
Default Configuration:
Guarantee
= volume
LUN reservation = on
Fractional_reserve
= 100%
Snap_reserve= 0%
Auto_delete
= off
Auto_grow
= off
Try_first
= NA
Fractional
Reserve
TestLUN
Available
space
30GB
30GB
40GB
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S M t D f lt
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Space Management Default
Configuration
Positives
Easy to manage/monitor space
Running out
of space only results in no additional
snapshots being created
SnapShots and active LUNs will always be available
Volumes are independent of each other
Negatives
Requires 2X + space
Puts us at a cost disadvantage versus competition
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Thin Provisioning Snapshot Space
Autodelete
Auto Delete Configuration:
Guarantee
= volume
LUN reservation = on
Fractional_reserve
= 0%
Snap_reserve= 20%
Auto_delete
= snap_reserve
Auto_grow
= on
Try_first
= snap_delete
LUN
Available
space
20GB
20GB
60GB
Snapshot
Available
(Snap Reserve)
Preferred Configuration #1
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Thi P i i i S h t S
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Thin Provisioning Snapshot Space
Autodelete
Positives
Easy to monitor/understand space
just volume (and .snapshot)
Sacrifices snapshots before active LUNs
Volumes are independent of each other
Looks like the competition
Negatives
Doesnt use shared space from the aggregate
(unless auto_grow
is also used)
Until ONTAP 7.3 have to be cautious with using
FlexClones
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Snapshot #1Snapshot #2
LUN #1 40GB
LUN #2 40GB
100% - 20 GB
Starting state
-
100GB Volume
- 2 x 40GB LUNs
-
snap_reserve = 20%
- fractional_reserve = 0%
Writing data to LUNs
Create snapshot #1Create snapshot #2
Volume is 100% full
Writes to LUNs are returned without of space
error messages
Application crashes!!
Filling Volume without autodelete
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Snapshot #1Snapshot #2
LUN #1 40GB
LUN #2 40GB
98% - 19.6GB
Writing data to LUNs
Create snapshot #1
Create snapshot #2
Snapshot #1 is autodeleted
Snapshot #2 is autodeleted
Snapshots are lost but applicationcontinues running
Filling Volume with autodelete
Starting state
-
100GB Volume
-
2 x 40GB LUNs
- snap_reserve = 20% - fractional_reserve = 0%
- trigger = snap_reserve
-
delete_order = oldest_first
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Thin Provisioning Snapshot Space
Vol Auto Size
Auto Grow Configuration:
Guarantee
= volume
LUN reservation = on
Fractional_reserve
= 0%
Snap_reserve= 0% (or X%)
Auto_delete
= volume
Auto_grow
= on
Try_first
= auto_grow
LUN
Available
space
70GB
30GB
Preferred Configuration #2
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Thi P i i i S h t S
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Thin Provisioning Snapshot Space
Auto Size
Positives
Uses shared free space from the aggregate for
possible growth
Sacrifices snapshots before active LUNs
Can tune amount of thin provisioning per volume
Works even with a smaller number of volumes Negatives
Volumes are not completely independent of oneanother
Always the case when using shared free space
Growth in one volume can limit growth of another
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V l t i E l
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Volume autosize Example
vol aut osi ze vol 1 m 800gb i 150gb on
The current volume is 500GB
There are 2 LUNs
(160GB)
So with these 4 Snapshot copies, the volume is 98% full
Volume is 98%
full
LUN1 - 95GB
LUN2 95GB
Snapshot1 100GB
Snapshot 2 75GB
Snapshot 3 60GB
Snapshot 4 65GB
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V l t i E l ( t )
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Volume autosize Example (cont.)
vol aut osi ze vol 1 m 800gb i 150gb on
Now vol1 is 650GB, leaving 25 percent free space
LUN1 - 95GB
LUN2 95GB
Snapshot1 100GB
Snapshot 2 75GB
Snapshot 3 60GB
Snapshot 4 65GB
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Volume t i Example (cont )
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Volume autosize Example (cont.)
vol aut osi ze vol 1 m 800gb i 150gb on
Snapshot5, 145GB is added to the volume
LUN1 - 95GB
LUN2 95GB
Snapshot1 100GB
Snapshot 2 75GB
Snapshot 3 60GB
Snapshot 4 65GB
Snapshot 5 145GB
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Volume t i Example (cont )
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Volume autosize Example (cont.)
vol aut osi ze vol 1 m 800gb i 150gb on
Vol1 = 800GB
Max Growth
LUN1 - 95GB
LUN2 95GB
Snapshot1 100GB
Snapshot 2 75GB
Snapshot 3 60GB
Snapshot 4 65GB
Snapshot 5 145GB
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Configuration Options
Guarantee:
fractional
reservation:
snap
reserve: Trigger: Comment:
Volume 0% Y% volume
Probably doesn't make sense unless NAS data being written into the same
volume
Volume 0% (or X%) Y% (or 0%) snap_reserve
-Recommended config for auto delete
-
Easy to monitor free space
- Use fractional reserve >0% if using SME or SMSQL
Volume 0% Y% space_reserve -
Meaningless -
it will immediately delete every snapshot
Volume X% Y% volume
-
Probably doesn't make sense unless NAS data being written into the same
volume
Volume X% Y% snap_reserve
-
Easy to monitor amount of snapshot data
-
Provides some time if autodelete/autogrow
can't provide needed space
Volume X% Y% space_reserve -
Snapshot creation will be disabled when the volume is full
Volume 100% 0% N/A Default configuration for blocks
space overhead is very expensive
Volume 0% (or X%) 0% (or Y%) volume
-
Recommended config for auto_grow
-
Having fractional_reserve
set > 0% would provide some time if autodelete
or
autogrow
can't provide needed space, but can be confusing. Make fractional
reserve >0% if SME or SMSQL is used. Having SnapReserve
set to 20% would
also allow a trigger setting of snap_reserve
for snapshot deletes (if they were
enabled
but not for SQL or Exchange) and provide some snapshot buffer
space.
Volume X% 0% snap_reserve -
Meaningless -
it will immediately delete every snapshot
Volume X% 0% space_reserve -
Allows the use of the volume full warnings before snapshot deletion starts
File NA-100% 0% volume
-
Allows preference to newer snapshots by allowing new snapshots to be created
while deleting older
File NA-100% Y% snap_reserve-
Allows prefrence
to newer snapshots by allowing new snapshots to be created
while deleting older
File NA-100% Y% space_reserve - Meaningless - since fractional_reserve is 100%
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Recommendations Method #1 AutoDelete
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Recommendations Method #1 AutoDelete
First
Make sure you include adequate PS resourcing
Target snapshot space at 20%-70%
Set fractional reserve to 0, volume guarantee = volume.
Set Snap Reserve at default 20%
Enable snap auto delete (trigger=snap_reserve ortrigger=space_reserve) and vol auto size
Set try_first
= snap_delete
Change default setting of wafl_reclaim_threshold
to 90 (default 98) if
trigger=snap_reserve, or lower if space_reserve
Put the remainder of your free space in your aggregate (this becomesglobal free space) and will equate to about 50% but may vary on avolume-by-volume basis
Vol
auto size is used as a last resort in case the snapshots I have
cannot
be deleted
Over time I may manually reallocate some of my global space into
selected volumes to increase LUN sizes or provide more snap reserve
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Recommendations Method #2
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Recommendations Method #2
Auto_Grow First
Make sure you include adequate PS resourcing
Target snapshot space at 20%-70%
Set fractional reserve to 0, volume guarantee = volume..
Set Snap Reserve to 0
Enable snap auto delete (trigger=volume ortrigger=space_reserve) and vol
auto size
Set try_first
= volume_grow
Change default setting of wafl_reclaim_threshold
to 90 (default
98) remember the trigger for autogrow is always volume. Keep between 20% and 40% spare space in your volume (this isused for snapshot data but is not reserved for that purpose)
Put the remainder of your free space in your aggregate (thisbecomes global free space)
Snap delete is used only when the volume reaches max size orthere is no more space in aggregate.
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Recommendations - Exceptions
Size for performance first
Beware effects on performance if disk space
reduced DO NOT use snap auto delete
Instead use SME and SMSQL equivalents