HP 3PAR disk replacement.doc

8/19/2019 HP 3PAR disk replacement.doc

1/15

HP 3PAR disk replacement

December 15, 2015 Regmen HP 3PAR Tech Notes

HP 3PAR disk replacement. How to deal with failed

drive on 3PAR

This article treats of disk replacement on 3PAR for administrators who want to know

a little more about the background of disk replacement.

3PAR logical layer

With telling about disk replacement on 3PAR, the logical layer cannot be omited, as

this is the fundamental concern around hard drive replacement procedure on

3PAR. The logical layer of 3PAR consist few levels. n overall the structure is not

complicated, starting with physical disk and ending on !irtual !olumes.

physical disks "P#$ logical disks "%#$ &ommon Provisioning 'roups "&P's$→ → →

!irtual !olumes "!!$

Physical disks are divided into chunklets, starting with ())) series, we are talking

about *'+ -ed sie of chunklets. Then 3PAR is using chunklets to build %#s. This all

happen without any administrator involvement. &hunklet is the basic logic unit in

3PAR terminology. Thanks to this approach, we are receiving nicely virtualied

storage, with virtual RA# approach, which gives a lot of more /e-ibility, also in terms

of redundancy. 0rom the other hand, while some blocks within specic chunklet are

unreadable, then the whole chunklet "*'+$ is marked as failed.

3PAR and RAID protection

3PAR o1ers virtualied approach in RA# creation. RA# is created during &P'

creation and RA# behavior can be ad2usted by administrator according to needs.

RA# is based on chunklets, not on physical disks. Thanks to that we are in power to

create &P' based on performance, or we can use slower sectors within physical disk

to use them for e-ample for backup destaging, where performance is not so

important. Thanks to that we have full control on shaping our storage resources and

environment under.

0or e-ample to see the details on already created &P's, use showcpg command with

a suitable parameters.

3PAR-cluster cli% showcpg -sdg

http://www.regmen.com/hp-3par-disk-replacement/http://www.regmen.com/author/admin/http://www.regmen.com/category/hp-3par/hp-3par-tech-notes/http://www.regmen.com/author/admin/http://www.regmen.com/category/hp-3par/hp-3par-tech-notes/http://www.regmen.com/hp-3par-disk-replacement/


2/15

------(MB)------

Id Name War !imit "row Args

# $P"&$R' - - 3#* -t r' -ha cage -ss+ * -ss , -ch .rst -p -de/t0pe &$

, $P"112R' - - 3'* -t r' -ha cage -ss+ * -ss * -ch .rst -p -de/t0pe 112

$P"214A"IN" - - 3#* -t r' -ss+ * -ss , -ch last -p -de/t0pe &$

3 &$r, - - ''3 -ss+ -ha cage -t r, -p -de/t0pe &$

* &$r - - ''3 -ss+ -ha cage -t r -p -de/t0pe &$

' 112r, - - ,3* -ss+ -ha cage -t r, -p -de/t0pe 112

$P"112225P - - ''3 -t r' -ha cage -ss+ * -ss * -ch .rst -p -de/t0pe 112

The e-act working principle will be e-plained in the other article. owever for now, it

is good to know, that 3PAR allows to build RA# groups based on some capabilities4

• 5t4 type of RA#.

• 5ha4 here you can specify layout of RA# stripe sie distribution. The policy

can be based on cage "default$, magaine, backend port.

• 5ss4 option stands for set sie in terms of chunklets. #efault value is based

on specic RA#, for e-ample RA#5* 6 chunklets, RA#57 8 chunklets, RA#59

: chunklets.

•

5ss4 with this option it is possible to set5up step sie in kilobytes for• 5ch4 type of chunklets that would be preferred to build stripe "from

lowest;highest available in terms of numeration < outer;inner ones of disks$.

• 5p4 pattern is used for creating %#s in terms of disk type "0&, ==#, >%$

How 3PAR deals with spares

=ome chunklets are promoted for spares during rst set up a system. The 3PAR

algorithms build chunklets from physical disks to ma-imie the usage of outer ones

within disk. As spares chunklets should be used only temporarily in emergencysituation, 3PAR decided to assign spare chunklets on the inner ones of disk. The

details of spare chunklets visible on your 3PAR can be shown with showspare

command.

3PAR-cluster cli% showspare

#eep investigation is not needed to see that the numeration of spare chunklets on

each drive has high number, hence chunklets designated for spares are from inner

ones of disks, which is obviously good.


3/15

+ut that?s not all. The amount of chunklets that are candidates for spares are

determined by policy, which can be chosen by following vendor recommendation

from presents or chosen by us. We can distinguish below sparing algorithms4

• default4 amount of one full disk for every 8) disks, with re@uired 8 disks as

minimum.

• minimum4 same as default, but without re@uired minimum drives.

• ma-imum4 amount of one full disk per drive cage < so called cage level high

availabilityB.

• custom4 dened by user, but administrator should remember to add spares

while adding new drives.

Remember about vendor recommendation to create spare chunklets during rst

system initialiation, as this is the time when layout of created system is established

and specic chunklets can be distributed evenly among all physical disks.

Logging logical drive and spares?

n case of physical disk failure all new writes that would be committed to failed drive,

are redirected to logging logical disk. When drive come back online or time limit for

logging is reached, then reallocation is performed to free chunklets marked as spare

chunklets.

To see %ogical #isk that are marked as logging disks, grep log from showpd

command as shown below.

ssh 3PAR-cluster showpd 6grep log

Id Name RAI2 -2etailed1tate- 7w 1i+eMB 5sedMB 5se !gct !gId

W4hru Map8

' log#9# , ormal #:-:-:- #*# # log # --- ; N

log,9# , ormal ,:-:-:- #*# # log # --- ; N

< log9# , ormal :-:-:- #*# # log # --- ; N

log39# , ormal 3:-:-:- #*# # log # --- ; N

0ollowing oCcial guide, we can investigate informations related to logging drives,

which are4

• &olumn Dse4 log in cell under this column means that logical disk is used as a

logging logical disk.

• &olumn %gct4 The number of chunklets that are in logging mode in the logical

disk.


4/15

• &olumn %gd4 The # of the logging disk that is being used for logging by the

logical disk.

Important information

!oggig logical dis= is etit0 that is etirel0 created ad maaged >0 3PAR

s0stem9

Replacing failed disk

The most common task on any storage array is to deal with failed drives. =torage

arrays makes tremendous work with our data, especially if cache hit is not on the

remarkable level. The @uestion is, how to deal with failed drive, and what should be

under our attention.

The 3PAR is starting spit out many alerts regarding some disk, marking that situation

become serious.

#,'-,-# #*?3?3 "M4 # I@ormatioal 2is= e/et

hwdis=?'###$'##l=?#'ee3 >l=ct #,

@rucd?#3 !5N?# !5NWWN?################ a@ter #9##


5/15

#,'-,-# #*?*


6/15

Id $agePos 1tate ----NodeWWN---- --M&R-- -----Model------ -1erial- -&WRe/-

Protocol Media40pe -----Admissio4ime-----

< #?


7/15

$hu=lets mar=ed @or mo/ig? ased o F secods per chu=let is?

hours miutes ad , secods

ser/icemag resume # < -- is i Progress

Dnfortunately above method is not *))F reliable, and from time to time, the

amount of chunklets and time for that operations are wrongly displayed. To check

how the process looks like you can use showpdch command with 5mov parameter.

At the end of output sum of chunklets remaining for move is shown.

3PAR-cluster cli% showpdch -mo/ ,#

hat if I want replace disk man!ally?

f you see that this is only a matter of time, when your disk fail, and you possess

some spare drive in your closet, then you free to do it on your own.

Gou can do this at least on both ways. The most common is to use servicemag utility,

but from time to time for some reasons command fail and disk replacement is not

possible.

%et?s say that our disk layout looks like on image presented below.


8/15

The


9/15

add


10/15

6. >ow you can initiate the movement process for data from specied physical

disk to location chosen by system, which is one of the main steps in terms of

disk replacement.

The suitable command is movepdtospare with 5vacate option. !acate optionmakes moves pernament and removes source tags after recolocation. The 5f

parameter means that no conrmation is re@uired.

n case this command fail, you will be forced to do it manually, chunklet by

chunklet.

http://www.regmen.com/wp-content/uploads/2015/12/image004.pnghttp://www.regmen.com/wp-content/uploads/2015/12/image003.png


11/15

3PAR-cluster cli% mo/ech -perm -o/rd Lpdid?Lchu=letlocatio

where4

5perm4 chunklet are moved pernamently and original location will be forgot.

5ovrd4 allows to move chunklet to some destination even if it will have impact

on @uality. Hption is necessary with 5perm parameter.

3. Time to see whether we have any spare chunklets on disk designated for

removal, as previous step only moved data chunklets.

To display chunklets marked as spare use showpdch 5spr command.

3PAR-cluster cli% showpdch -spr Lpdid


12/15

8. Time to see whether we have any spare chunklets on disk designated for

removal, as previous step only moved data chunklets.

http://www.regmen.com/wp-content/uploads/2015/12/image005.png


13/15

&ommand designated for that kind of task is shown below. t will remove all

spare chunklets o1 the disk. After e-ecution check again whether any spares

e-ist.

3PAR-cluster cli% remo/espare Lpdid?a

7. After all previous steps you can safely remove physical disk defnition from

system. old on with physical disk replacement at this step.

3PAR-cluster cli% dismisspd Lpdid

9. &heck if dismissed disk shown us new. f yes, then it can be safely remove

from magaine.

http://www.regmen.com/wp-content/uploads/2015/12/image007.pnghttp://www.regmen.com/wp-content/uploads/2015/12/image006.png


14/15

(. n case you put in new disk and disk will not be automatically added to the

system, you have to do it manually

http://www.regmen.com/wp-content/uploads/2015/12/image008.png


15/15

0irst thing is to determine the WW> of disk. &heck this with showpd 5i

command.

3PAR-cluster cli% showpd -i Lpdid

After that use admitpd command to make new disk operational for system.

3PAR-cluster cli% admitpd Ldis=ww

At the end, tunesys is necessary to make the proper layout of chunklets

within &P's.

3PAR-cluster cli% tues0s
http://www.regmen.com/wp-content/uploads/2015/12/image013.pnghttp://www.regmen.com/wp-content/uploads/2015/12/image012.jpghttp://www.regmen.com/wp-content/uploads/2015/12/3par_wwn_disk.png

HP 3PAR disk replacement.doc

Documents

Transcript of HP 3PAR disk replacement.doc