Home > Articles > Operating Systems, Server > Solaris

This chapter is from the book

This chapter is from the book

2.7 Replacing Bad Devices Automatically

ZFS has the capability to replace a disk in a pool automatically without intervention by the administrator. This feature, known as autoreplace, is turned off by default. This feature will allow ZFS to replace a bad disk with a spare from the spares pool, automatically allowing the pool to operate at optimum performance. This allows the administrator to replace the failed drive at a later time. The manual disk replacement procedure is covered later in this chapter.

If you list the properties of the ZFS pool, you can see that the autoreplace feature is turned off using the get subcommand.

1   # zpool get all mpool
2   NAME   PROPERTY       VALUE       SOURCE
3   mpool  size           234M        -
4   mpool  used           111K        -
5   mpool  available      234M        -
6   mpool  capacity       0%          -
7   mpool  altroot        -           default
8   mpool  health         DEGRADED    -
9   mpool  guid           11612108450022771594  -
10  mpool  version        13          default
11  mpool  bootfs         -           default
12  mpool  delegation     on          default
13  mpool  autoreplace    off         default
14  mpool  cachefile      -           default
15  mpool  failmode       wait        default
16  mpool  listsnapshots  off         default

To turn on the autoreplace feature, use the following command line:

# zpool autoreplace=on mpool

To simulate a bad device, I shut down the system and removed c5t4d0 from the system. The system now cannot contact the disk and has marked the removed disk as unavailable. With the system rebooted, you can examine the output of the zpool status command:

1   $ zpool status mpool
2   pool: mpool
3   state: DEGRADED
4   status: One or more devices could not be opened.  Sufficient replicas exist for
5   the pool to continue functioning in a degraded state.
6   action: Attach the missing device and online it using 'zpool online'.
7   see: http://www.sun.com/msg/ZFS-8000-2Q
8   scrub: resilver completed after 0h0m with 0 errors on Mon Apr  6 00:52:36 2009
9   config:
10
11  NAME           STATE     READ WRITE CKSUM
12  mpool          DEGRADED     0     0     0
13    mirror       ONLINE       0     0     0
14      c5t2d0     ONLINE       0     0     0
15      c5t3d0     ONLINE       0     0     0
16    mirror       DEGRADED     0     0     0
17      spare      DEGRADED     0     0     0
18        c5t4d0   UNAVAIL      0    89     0  cannot open
19        c5t14d0  ONLINE       0     0     0  31K resilvered
20      c5t5d0     ONLINE       0     0     0  31K resilvered
21  spares
22    c5t14d0      INUSE     currently in use
23
24  errors: No known data errors

On line 3, the state of the pool has been degraded, and line 4 tells you that the pool can continue in this state. On lines 6 and 7, ZFS tells you what actions you will need to take, and by going to the Web site, a more detailed message tells you how to correct the problem. Line 19 tells you that the spare disk has been resilvered with disk c5t5d0. Line 22 now gives you the new status of the spare disk c5t14d0.

The original definition of resilver is the process of restoring a glass mirror with a new silver backing. In ZFS, it is a re-creation of data by copying from one disk to another. In other volume management systems, the process is called resynchronization. Continuing the example, you can shut down the system and attach a new disk in the same location of the missing disk. The new disk at location c5t4d0 is automatically resilvered to the mirrored vdev, and the spare disk is put back to an available state.

$ zpool status mpool
pool: mpool
state: ONLINE
scrub: resilver completed after 0h0m with 0 errors on Mon Apr  6 02:21:05 2009
config:

NAME        STATE     READ WRITE CKSUM
mpool       ONLINE       0     0     0
  mirror    ONLINE       0     0     0
    c5t2d0  ONLINE       0     0     0
    c5t3d0  ONLINE       0     0     0
  mirror    ONLINE       0     0     0
    c5t4d0  ONLINE       0     0     0  23K resilvered
    c5t5d0  ONLINE       0     0     0  23K resilvered
 spares
  c5t14d0   AVAIL

errors: No known data errors

If the original disk is reattached to the system, ZFS does not handle this case with the same grace. Once the system is booted, the original disk must be detached from the ZFS pool. Next, the spare disk (c5d14d0) must be replaced with the original disk. The last step is to place the spare disk back into the spares group.

$ pfexec zpool detach mpool c5t4d0
$ pfexec zpool replace mpool c5t14d0 c5t4d0
$ pfexec zpool add mpool spare c5t14d0
$ zpool status mpool
pool: mpool
state: ONLINE
scrub: resilver completed after 0h0m with 0 errors on Mon Apr  6 02:50:25 2009
config:

NAME        STATE     READ WRITE CKSUM
mpool       ONLINE       0     0     0
  mirror    ONLINE       0     0     0
    c5t2d0  ONLINE       0     0     0
    c5t3d0  ONLINE       0     0     0
  mirror    ONLINE       0     0     0
    c5t4d0  ONLINE       0     0     0  40.5K resilvered
    c5t5d0  ONLINE       0     0     0  40.5K resilvered
spares
  c5t14d0   AVAIL

errors: No known data errors

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020