Red Hat ENTERPRISE LINUX - ONLINE STORAGE RECONFIGURATION GUIDE BETA Informations techniques

Red Hat Subject Matter ExpertsJosef BacikKamil Dudka Hans de Goede Doug LedfordDaniel Novotny Nathan Straz David WysochanskiContributors Michael Chris

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WarningDo not attempt to resize a partition on a device that is in use.Pro ced u re 13.4 . Resiz e a part it ion1. Before resizing a partition, boot

Chapter 14. LVM (Logical Volume Manager)LVM is a tool for logical volume management which includes allocating disks, striping, mirroring andresizing l

Fig ure 14 .2. Lo g ical Vo lu mesOn the other hand, if a system is partitioned with the ext3 file system, the hard drive is divided intopartitions of

In the example used in this section, the following are the details for the volume group that wascreated during the installation:Examp le 14 .1. Creat

Fig ure 14 .4 . Ph ysical View Win d o wThe figure below illustrates the logical view for the selected volume group. The individual logicalvolume size

Volume window from which you can modify the Logical volume name, size (in extents, gigabytes,megabytes, or kilobytes) and also use the remaining space

In this example, partition 3 will be initialized and added to an existing volume group. To initialize apartition or unpartioned space, select the part

Fig ure 14 .7. Un allo cat ed Vo lu mesClicking on the Ad d to Exi sti ng Vo l ume G ro up button will display a pop-up window listingthe existing

select one of the existing logical volumes and increase the extents (see Section 14.2.6, “ Extendinga Volume Group” ),select an existing logical volum

Fig ure 14 .9 . Lo g ical view o f vo lu me g roup14 .2.3. Migrat ing Ext ent sTo migrate extents from a physical volume, select the volume from the

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Fig ure 14 .10. Mig rat e Ext en t sThe figure below illustrates a migration of extents in progress. In this example, the extents weremigrated to &apo

Fig ure 14 .12. Lo g ical an d p h ysical view o f vo lu me g ro u p14 .2.4 . Adding a New Hard Disk Using LVMIn this example, a new IDE hard disk w

Fig ure 14 .13. U n init ializ ed h ard d isk14 .2.5. Adding a New Volume GroupOnce initialized, LVM will add the new volume to the list of unalloca

The figure below illustrates the physical view of the new volume group. The new logical volumenamed 'Backups' in this volume group is also l

In this example, the objective was to extend the new volume group to include an uninitialized entity(partition). Doing so increases the size or number

Fig ure 14 .16 . Lo g ical an d p h ysical view o f an ext en ded vo lu me gro u p14 .2.7. Edit ing a Logical VolumeThe LVM utility allows you to

Fig ure 14 .17. Edit lo g ical volu meIf you wish to mount the volume, select the 'Mount' checkbox indicating the preferred mount point. To

Fig ure 14 .18. Edit lo g ical volu me - specif yin g mo u n t o p t io n sThe figure below illustrates the logical and physical view of the volum

Fig ure 14 .19 . Ed it lo g ical vo lu me14 .3. LVM ReferencesUse these sources to learn more about LVM.Installed Documentationrpm -q d l vm2 — This

Chapter 15. Swap SpaceSwap space in Linux is used when the amount of physical memory (RAM) is full. If the system needsmore memory resources and the R

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existing LVM2 logical volume. It is recommended that you extend an existing logical volume.15.1.1. Ext ending Swap on an LVM2 Logical VolumeBy default

# swapo n -v /d ev/Vo l G ro up0 0 /Lo gVo l 02To test if the logical volume was successfully created, use cat /pro c/swaps or free to inspect theswap

To reduce an LVM2 swap logical volume (assuming /d ev/Vo l G ro up0 0 /Lo g Vo l 0 1 is the volumeyou want to reduce):Pro ced u re 15.3. Red u cin g

# swapo ff -v /swapfi l e2. Remove its entry from the /etc/fstab file.3. Remove the actual file:# rm /swapfi le15.3. Moving Swap SpaceTo move swap s

Chapter 16. Disk QuotasDisk space can be restricted by implementing disk quotas which alert a system administrator before auser consumes too much disk

none /sys sysfs defaults 0 0 /dev/VolGroup00/LogVol02 /home ext3 defaults,usrquota,grpquota 1 2 /dev/VolGrou

If neither the -u or -g options are specified, only the user quota file is created. If only -g is specified,only the group quota file is created.Aft

The first column is the name of the file system that has a quota enabled for it. The second columnshows how many blocks the user is currently using. T

16.1.6. Set t ing t he Grace Period for Soft Limit sIf a given quota has soft limits, you can edit the grace period (i.e. the amount of time a soft l

Creating a disk usage report entails running the repq uo ta utility.Examp le 16 .5. O u t p u t o f repq uo ta comman dFor example, the command repq

Preface1. Document Convent ionsThis manual uses several conventions to highlight certain words and phrases and draw attention tospecific pieces of in

An alternative way to safely run q uo tacheck is to boot the system into single-user mode toprevent the possibility of data corruption in quota files

Chapter 17. Redundant Array of Independent Disks (RAID)The basic idea behind RAID is to combine multiple small, inexpensive disk drives into an array

Software RAIDSoftware RAID implements the various RAID levels in the kernel disk (block device) code. It offers thecheapest possible solution, as exp

capacity of the smallest member disk in a Hardware RAID or the capacity of smallestmember partition in a Software RAID multiplied by the number of dis

two drives in the array. This complex parity scheme creates a significantly higher CPUburden on software RAID devices and also imposes an increased bu

dmraidDevice-mapper RAID or d mrai d refers to device-mapper kernel code that offers the mechanism topiece disks together into a RAID set. This same k

As the name suggests, d mrai d is used to manage device-mapper RAID sets. The d mrai d tool findsATARAID devices using multiple metadata format han

[5] RAID level 1 c o mes at a hig h c o st b ecause yo u write the same info rmatio n to all o f the d isks in thearray, p ro vid es d ata reliab il

Chapter 18. Using the mo unt CommandOn Linux, UNIX, and similar operating systems, file systems on different partitions and removabledevices (CD s, DV

To list such mount points using the fi nd mnt command, type:~]$ fi nd mnt -t ext4TARGET SOURCE FSTYPE OPTIONS/ /dev/sda2 ext4 rw,realtime,se

C haracter T abl e. Double-click this highlighted character to place it in the T ext to co py field and then click the Co py button. Now switch back

Note: Determining the UUID and Label of a Particular DeviceTo determine the UUID and—if the device uses it—the label of a particular device, use the b

Older USB flash drives often use the FAT file system. Assuming that such drive uses the /d ev/sd c1 device and that the /med i a/fl ashd isk/ director

18.2.3. Sharing Mount sOccasionally, certain system administration tasks require access to the same file system from morethan one place in the directo

~]# mo unt /d ev/cd ro m /med ia/cd ro m~]# l s /med i a/cd ro mEFI GPL isolinux LiveOS~]# l s /mnt/cd ro mEFI GPL isolinux LiveOSSimilarly, it

~]# l s /mnt/cd ro mEFI GPL isolinux LiveOSAlso verify that file systems mounted in the /mnt directory are not reflected in /med i a.For instance,

It is also possible to verify that file systems mounted in the /mnt directory are notreflected in /med i a. For instance, if a non-empty USB flash dri

An NFS storage contains user directories and is already mounted in /mnt/userd i rs/. As ro o t,move this mount point to /ho me by using the following

The following resources provide an in-depth documentation on the subject.18.4 .1. Manual Page Document at ionman 8 mo unt — The manual page for the mo

Chapter 19. The vo l ume_key functionThe volume_key function provides two tools, libvolume_key and vo l ume_key. libvolume_key is alibrary for manipul

This operation does not permanently alter the volume by adding a new passphrase, forexample. The user can access and modify the decrypted volume, modi

before, " "so cannot be deassigned\n", __func__); r = -EINVAL; goto out;

vo l ume_key --save /path/to/volume -o escro w-packetA prompt will then appear requiring an escrow packet passphrase to protect the key.2. Save the

At this point it is possible to choose an NSS database password. Each NSS database canhave a different password so the designated users do not need to

After providing the NSS database password, the designated user chooses a passphrase forencrypting escro w-packet-o ut. This passphrase can be differen

Chapter 20. Access Control ListsFiles and directories have permission sets for the owner of the file, the group associated with the file,and all other

4. For users not in the user group for the fileThe setfacl utility sets ACLs for files and directories. Use the -m option to add or modify the ACL o

To set a default ACL, add d : before the rule and specify a directory instead of a file name.Examp le 20.3. Set t in g d ef au lt ACLsFor example,

addition, the -a option (equivalent to -d R --preserve= al l ) of cp also preserves ACLs during abackup along with other information such as timestam

man acl — D escription of ACLsman g etfacl — Discusses how to get file access control listsman setfacl — Explains how to set file access control li

Chapter 21. Solid-State Disk Deployment GuidelinesSolid-state disks (SSD ) are storage devices that use NAND flash chips to persistently store data. T

As of Red Hat Enterprise Linux 6.4, ext4 and XFS are the only fully-supported file systems thatsupport d i scard . Previous versions of Red Hat Enterp

Red Hat also hosts a large number of electronic mailing lists for discussion of Red Hat software andtechnology. You can find a list of publicly availa

Chapter 22. Write BarriersA write barrier is a kernel mechanism used to ensure that file system metadata is correctly written andordered on persistent

To mitigate the risk of data corruption during power loss, some storage devices use battery-backedwrite caches. Generally, high-end arrays and some ha

Most controllers use vendor-specific tools to query and manipulate target drives. For example, theLSI Megaraid SAS controller uses a battery-backed wr

Chapter 23. Storage I/O Alignment and SizeRecent enhancements to the SCSI and ATA standards allow storage devices to indicate theirpreferred (and in s

Storage vendors can also supply I/O hints about the preferred minimum unit for random I/O(mi ni mum_i o _si ze) and streaming I/O (o pti mal _i o _si

BLKSSZG ET : l o g i cal _bl o ck_si zeBLKIO MIN: mi ni mum_i o _si zeBLKIO OP T : o pti mal _i o _si ze23.3. St andardsThis section describes I/O sta

All layers of the Linux I/O stack have been engineered to propagate the various I/O parameters up thestack. When a layer consumes an attribute or aggr

determine the I/O parameters of a device for optimal placement of all partitions. The fd i sk utility willalign all partitions on a 1MB boundary.parte

Chapter 24. Setting Up A Remote Diskless SystemThe Network Booting Service (provided by system-co nfi g -netbo o t) is no longer available inRed Hat E

After configuring a tftp server, you need to set up a DHCP service on the same host machine. Referto the Red Hat Enterprise Linux 6 Deployment Guide f

Chapter 1. OverviewThe Storage Administration Guide contains extensive information on supported file systems and datastorage features in Red Hat Enter

# cp /boot/vmlinuz-kernel-version /var/lib/tftpboot/3. Create the ini trd (i.e. ini tramfs-kernel-version. i mg ) with network support:# dracut init

Chapter 25. Online Storage ManagementIt is often desirable to add, remove or re-size storage devices while the operating system is running,and withou

po rt_name — 64-bit port nameRemo t e Po rt : /sys/cl ass/fc_remo te_po rts/rpo rt-H: B-R/po rt_i dno d e_namepo rt_named ev_l o ss_tmo — number of s

Remote Port d ev_l o ss_tmoX X X X XRemote Port fast_i o _fai l _tmoX X ⁠X ⁠XHost po rt_i d X X X X XHost i ssue_l i pX X Xl pfc q l a2xxx zfcp mptfc

This command displays the session/device state, session ID (sid), some negotiated parameters, andthe SCSI devices accessible through the session.For s

servi ce tg td startSt o p p in g t he t g t d serviceTo stop the tgtd service, run:servi ce tg td sto pIf there are open connections, use:servi c

In addition, path-based names are system-specific. This can cause unintended data changes whenthe device is accessed by multiple systems, such as in a

When the user_fri end l y_names feature (of device- map p er- mu lt ip at h ) is used, the WWID ismapped to a name of the form /d ev/mapper/mpathn. By

Pro ced u re 25.1. En su rin g a Clean D evice Remo val1. Close all users of the device and backup device data as needed.2. Use umo unt to unmount

Pro ced u re 25.2. Remo vin g a Pat h t o a St o rag e Device1. Remove any reference to the device's path-based name, like /d ev/sd or /d ev

The ext4 file system is fully supported in this release. It is now the default file system of Red HatEnterprise Linux 6, supporting an unlimited numbe

NoteThe older form of this command, echo "scsi ad d -si ng l e-d evi ce 0 0 0 0 " > /pro c/scsi /scsi , is deprecated.a. In some Fi

another device that is already configured on the same path as the new device. This can bedone with various commands, such as l sscsi , scsi _i d , mul

NoteThese commands will only work if the d cbd settings for the Ethernet interface were notchanged.5. Load the FCoE device now using:# ifconfig ethX

Pro ced u re 25.5. Co n f ig u re FCo E t arg et1. Setting up an FCoE target requires the installation of the fco e-targ et-uti l s package,along wit

/> tcm_fc/ create 00:11:22:33:44:55:66:77If FCoE interfaces are present on the system, tab-completing after create will list availableinterfaces. I

mount_fcoe_disks_from_fstab() { local timeout=20 local done=1 local fcoe_disks=($(egrep 'by-path\/fc-.*_netdev' /etc/fstab | cut

25.9. Scanning St orage Int erconnect sThere are several commands available that allow you to reset and/or scan one or moreinterconnects, potentially

The default iSCSI configuration file is /etc/i scsi /i scsi d. co nf. This file contains iSCSIsettings used by i scsi d and i scsi ad m.During target

$ ping -I ethX target_IPIf pi ng fails, then you will not be able to bind a session to a NIC. If this is the case, check the networksettings first.25

For software iSCSI, each i face configuration must have a unique name (with less than 65characters). The i face_name for network devices that support

⁠Part I. File SystemsThe File Systems section explains file system structure followed by two technology previews: eCryptfsand Btrfs. This is followed

# iscsiadm -m iface -I iface_name --op=update -n iface.setting -v hw_addressExamp le 25.12. Set MAC ad d ress o f i face0For example, to set the MAC

This behavior was implemented for compatibility reasons. To override this, use the -I iface_nameto specify which portal to bind to an i face, as in:#

The output will appear in the following format:target_IP:port,target_portal_group_tag proper_target_nameExamp le 25.14 . Usin g i scsi ad m t o issu

If your device supports multiple targets, you will need to issue a send targ ets command to the hoststo find new portals for each target. Then, rescan

Examp le 25.17. Fu ll i scsi ad m co mman dUsing our previous example (where proper_target_name is eq ual l o g i c-i scsi 1), the fullcommand would b

In most cases, fully resizing an online logical unit involves two things: resizing the logical unit itselfand reflecting the size change in the corres

NoteYou can also re-scan iSCSI logical units using the following command:# iscsiadm -m node -R -I interfaceReplace interface with the corresponding in

1. Dump the device mapper table for the multipathed device using:d msetup tabl e multipath_device2. Save the dumped device mapper table as table_nam

To change the R/W state, use the following procedure:Pro ced u re 25.7. Ch an g e t h e R /W st at e1. To move the device from RO to R/W, see step 2.

# mul ti path -rThe mul ti path -11 command can then be used to confirm the change.25.1 4 .4 .3. Do cument at io nFurther information can be found in

Chapter 2. File System Structure and MaintenanceThe file system structure is the most basic level of organization in an operating system. The way anop

Pro ced u re 25.8. Det ermin in g T h e St at e o f a Remo t e Po rt1. To determine the state of a remote port, run the following command:$ cat/sys

When d m-mul ti path is being used, the SCSI layer will fail those running commands and defer themto the multipath layer. The multipath layer then ret

ImportantWhether your considerations are failover speed or security, the recommended value for repl acement_ti meo ut will depend on other factors. Th

The Linux SCSI layer sets a timer on each command. When this timer expires, the SCSI layer willquiesce the host bus adapter (HBA) and wait for all out

Pro ced u re 25.10. Wo rkin g Aro und St ale Lo g ical U n it s1. Determine which mpath link entries in /etc/l vm/cache/. cache are specific tothe s

Chapter 26. Device Mapper Multipathing and Virtual StorageRed Hat Enterprise Linux 6 also supports DM-Multipath and virtual storage. Both features are

(the cable, switch, or controller) fails, DM-Multipath switches to an alternate path.Impro ved Perf ormanceDM-Multipath can be configured in active/a

Revision HistoryRevisio n 2- 52 Wed Mar 25 2015 Jacq u elynn EastAdded ext back up and restore chaptersRevisio n 2- 51 T h u O ct 9 2014 Jacq u

Added fsck section BZ #904902.Revisio n 2- 27 T h u Sep 05 2013 Jacq u elyn n EastEdited Chapter 9: Network File System (NFS).Revisio n 2- 26 Mon

BZ #894697 Updated sections regarding FCoE.Revisio n 2- 4 Mon Jan 14 2013 Jacq u elyn n EastBZ #894891 As pNFS is coming out of tech preview statu

11675568 6272120 4810348 57% / /dev/sda1 100691 9281 86211 10% /bootnone 32

- enabling disk quotas with, Enabling Quotas/local/d irect o ry ( clien t co n f ig u rat io n , mo u n t in g )- NFS, NFS Client Configuration/p ro

addin g p at h s t o a st o rag e d evice, Ad d in g a St o rag e Device o r Pat haddin g /remo vin g- LUN (logical unit number), Adding/Removing a

- I/O alignment and size, Block Device ioctlsb lo cked d evice, verif yin g- fibre channel- modifying link loss behavior, Fibre Channelb ru n ( cach

Ch an g in g the read /writ e st at e- Online logical units, Changing the Read/Write State of an Online Logical Unitchan n el co mman d wo rd ( CCW

- solid state disks, Solid-State Disk Deployment Guidelinesd et ermin in g remo t e p o rt st at es- fibre channel- modifying link loss behavior, Fi

d isab lin g writ e cach es- write barriers, Disabling Write Cachesd isco very- iSCSI, iSCSI D iscovery Configurationd isk q u o t as, Disk Q uo t as

e2f sck, Revert in g t o an Ext 2 File Syst eme2imag e ( o t h er ext 4 f ile syst em ut ilit ies)- ext4, Other Ext4 File System Utilitiese2lab el-

ext4- allocation features, The Ext4 File System- creating, Creating an Ext4 File System- debugfs (other ext4 file system utilities), Other Ext4 File S

f ib re- ch an n el o ver et hern et- storage considerations during installation, Updates to Storage Configuration DuringInstallationf ile syst em- FH

- ext4, The Ext4 File System- XFS, The XFS File SystemGg et f acl , Ret rievin g ACLsG FS2- file system types, Global File System 2- gfs2.ko, Global

Fig ure 2.1. G N O ME Syst em Mo n it o r File Syst ems t ab2.1 .1 .2 . T he /bo o t/ Direct o ryThe /bo o t/ directory contains static files required

- tools (for partitioning and other file system functions), Partition and File SystemTools- userspace access, Userspace AccessI/O limit pro cessin g

- auto-partitioning and /home, Updates to Storage Configuration During Installation- basic path, Updates to Storage Configuration During Installation-

iSCSI lo g ical un it , resiz in g , Resiz in g an iSCSI Lo g ical Un itiSCSI root- iSCSI configuration, iSCSI Rootissu e_lip- fibre channel API, Fi

- adding a new volume group, Adding a New Volume Group- additional resources, LVM References- documentation, LVM References- editing a logical volume,

- fibre channel, Fibre Channelmo unt (clien t co nf igurat ion)- NFS, NFS Client Configurationmo unt (co mman d ) , Usin g the mo u n t Co mman d-

- autofs version 5, Improvements in autofs Version 5 over Version 4- client- autofs , autofs- configuration, NFS Client Configuration- mount options,

- FS-Cache, Using the Cache With NFSn o b arrier mo u n t o pt io n- ext4, Mounting an Ext4 File System- XFS, Write BarriersNO P- O u t req uest s-

Parallel N FS- pNFS, pNFSp aramet ers f o r st o rag e access- I/O alignment and size, Parameters for Storage Accessp arit y- RAID, RAID Levels and Li

- overview, I/O Limit Processingp ro ject limit s ( set t in g )- XFS, Setting Project Limitsp ro p er n sswit ch conf ig u rat io n ( au t o f s v

- NFS, NFS over RDMAREAD CAPAC ITY( 16 )- I/O alignment and size, SCSIreco rd t yp es- discovery- iSCSI, iSCSI D iscovery ConfigurationRed Hat En t

drive), and a pop-up window displaying the contents appears.T able 2.1. Examp les of co mmo n f iles in t h e /d ev d irect o ryFile Descrip t io n

- LUN (logical unit number), Adding/Removing a Logical Unit Throughrescan-scsi-bus.shresiz e2f s, Revert ing t o an Ext 2 File Syst emresiz e2f s (

- storage considerations during installation, Separate Partitions for /home, /opt,/usr/localserver (clien t co n f igurat ion, mo u n t in g )- NFS,

- FS-Cache, Statistical Informationst o rag e access p aramet ers- I/O alignment and size, Parameters for Storage Accessst o rag e co n sid erat io ns

- XFS, Suspending an XFS File Systemsw ( mkf s.xf s su b - o p t io n s)- XFS, Creating an XFS File Systemswap ( t u n in g)- solid state disks, Swap

t f t p service, co nf igurin g- diskless systems, Configuring a tftp Service for Diskless Clientst h ro u g h p u t classes- solid state disks, Sol

- LVM, Utilizing Uninitialized EntitiesUn iversally Un iq u e Id ent if ier (UUID )- persistent naming, UUID and Other Persistent Identifiersu n moun

volu me_key- commands, Commands- individual user, Using volume_key as an individual userWwh at ' s n ew- storage considerations during installati

- report (xfs_quota expert mode), XFS Quota Management- simple mode (xfsrestore), Simple Mode for xfsrestore- su (mkfs.xfs sub-options), Creating an X

xf s_md rest o re- XFS, Other XFS File System Utilitiesxf s_met ad u mp- XFS, Other XFS File System Utilitiesxf s_q u o t a- XFS, XFS Quota Management

/o pt/packagename/man/.2.1 .1 .9 . T he /pro c/ Direct o ryThe /pro c/ directory contains special files that either extract information from the kerne

NoteThe default httpd install uses /var/www/html for served content.2.1 .1 .1 2 . T he /sys/ Dire ct o ryThe /sys/ directory utilizes the new sysfs

/usr/srcThis directory stores source code./usr/tmp lin ked t o /var/tmpThis directory stores temporary files.The /usr/ directory should also contain

/var/ftp//var/g d m//var/kerbero s//var/l i b//var/l o cal //var/l o ck//var/l o g //var/mai l linked to /var/spo ol /mai l //var/mai l man//var/name

/var/spo o l /po stfi x//var/spo o l /repackag e//var/spo o l /rwho //var/spo o l /samba//var/spo o l /sq ui d //var/spo o l /sq ui rrel mai l //var/s

Contains current information on multiple-disk or RAID configurations on the system, if theyexist./p ro c/mo u n t sLists all mounts currently used by

Red Hat Enterprise Linux 6 Storage Administration GuideDeploying and configuring single-node storage in Red Hat Enterprise Linux6Edition 2Jo sef Bacik

Chapter 3. Encrypted File SystemRed Hat Enterprise Linux 6 provides a technology preview of eCryptfs, a "pseudo-file system" whichprovides d

After the last step of an interactive mount, mo unt will display all the selections made and perform themount. This output consists of the command-lin

Chapter 4. BtrfsBtrfs is a new local file system under active development. It aims to provide better performance andscalability which will in turn ben

Chapter 5. The Ext3 File SystemThe ext3 file system is essentially an enhanced version of the ext2 file system. These improvementsprovide the followin

The Red Hat Enterprise Linux 6 version of ext3 features the following updates:Def au lt Inod e Siz es Ch an g edThe default size of the on-disk inode

NoteA default installation of Red Hat Enterprise Linux uses ext4 for all file systems. However, toconvert ext2 to ext3, always use the e2fsck utility

# mo unt -t ext2 /dev/mapper/VolGroup00-LogVol02 /mount/pointIn the above command, replace /mount/point with the mount point of the partition.NoteIf a

Chapter 6. The Ext4 File SystemThe ext4 file system is a scalable extension of the ext3 file system, which was the default file system ofRed Hat Enter

The ext4 file system also supports the following:Extended attributes (xattr) — This allows the system to associate several additionalname and value pa

For striped block devices (for example, RAID5 arrays), the stripe geometry can be specified at the timeof file system creation. Using proper stripe ge

[email protected] Sto rageDavid HowellsServer Development Hardware Enablementdho [email protected] LehmanBase Operating System Insta

By default, ext4 uses write barriers to ensure file system integrity even when power is lost to a devicewith write caches enabled. For devices without

LABEL=/data /data ext3 defaults 0 0tmpfs /dev/shm tmpfs defaults 0 0devpts /dev/pt

NoteIf using standard redirection, the '-f' option must be passed separately.# dump -0u -f - /dev/sda1 | ssh root@ remoteserver.example.com

# mkdir /mnt/sda3# mount -t ext3 /dev/sda3 /mnt/sda3# mkdir /backup-files# mount -t ext3 /dev/sda6 /backup-files6. Restore the data.# cd /mnt/sda1# r

e2imag eSaves critical ext2, ext3, or ext4 file system metadata to a file.For more information about these utilities, refer to their respective man pa

Chapter 7. Global File System 2The Red Hat Global File System 2 (GFS2) is a native file system that interfaces directly with the Linuxkernel file syst

Chapter 8. The XFS File SystemXFS is a highly scalable, high-performance file system which was originally designed at SiliconGraphics, Inc. It was cre

Examp le 8.1. mkfs. xfs co mmand ou t p u tBelow is a sample output of the mkfs. xfs command:meta-data=/dev/device isize=256 agcount=4,

# mo unt /d ev/device /mount/pointXFS also supports several mount options to influence behavior.XFS allocates inodes to reflect their on-disk location

d fShows free and used counts for blocks and inodes.In contrast, xfs_q uo ta also has an expert mode. The sub-commands of this mode allow actualconfig

Legal NoticeCo pyright © 20 13 Red Hat Inc. and others.This do cument is licensed by Red Hat under the Creative Commo ns Attributio n-ShareAlike 3.0U

ImportantWhile real-time blocks (rtbhard /rtbso ft) are described in man xfs_q uo ta as valid unitswhen setting quotas, the real-time sub-volume is no

# xfs_repai r /dev/deviceThe xfs_repai r utility is highly scalable and is designed to repair even very large file systems withmany inodes efficiently

XFS file system backup and restoration involves two utilities: xfsd ump and xfsresto re.To backup or dump an XFS file system, use the xfsd ump utility

start: ino 0 offset 0 end: ino 1 offset 0 interrupted: NO media files: 1 media file 0: mfile index: 0 mfile type: data mfile siz

For more information about dumping and restoring XFS file systems, refer to man xfsd ump and man xfsresto re.8.8. Ot her XFS File Syst em Ut ilit iesR

Chapter 9. Network File System (NFS)A Network File System (NFS) allows remote hosts to mount file systems over a network and interactwith those file s

ImportantIn order for NFS to work with a default installation of Red Hat Enterprise Linux with a firewallenabled, configure IPTables with the default

The following RPC processes facilitate NFS services:rp c.mo untdThis process is used by an NFS server to process MO UNT requests from NFSv2 and NFSv3

$ l smo d | g rep nfs_l ayo ut_nfsv4 1_fi l esAnother way to verify a successful NFSv4.1 mount is with the mo unt command. The mount entry inthe out

9.3.1. Mount ing NFS File Syst ems using /etc/fstabAn alternate way to mount an NFS share from another machine is to add a line to the /etc/fstabfile.

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ImportantThe nfs-utils package is now a part of both the 'NFS file server' and the 'Network File SystemClient' groups. As such, it

increasingly better at handling the NSS configuration, it is still not complete. Autofs version5, on the other hand, is a complete implementation.Refe

The following is a sample line from /etc/auto .master file (displayed with cat /etc/auto .master):/home /etc/auto.miscThe general format of maps is si

# servi ce auto fs status9.4 .3. Overriding or Augment ing Sit e Configurat ion FilesIt can be useful to override site defaults for a specific mount

This last example works as expected because auto fs does not include the contents of a file map ofthe same name as the one it is reading. As such, aut

# /home, auto.master, example.comdn: automountMapName=auto.master,dc=example,dc=comobjectClass: automountcn: /homeautomountKey: /homeautomountInformat

lo o ku p cach e= modeSpecifies how the kernel should manage its cache of directory entries for a given mountpoint. Valid arguments for mode are al l

setting is sec= sys, which uses local UNIX UID s and GIDs by using AUT H_SY S toauthenticate NFS operations.sec= krb5 uses Kerberos V5 instead of loca

# servi ce nfs restartThe co nd restart (conditional restart) option only starts nfs if it is currently running. This option isuseful for scripts,

It is possible to specify multiple hosts, along with specific options for each host. To do so, list themon the same line as a space-delimited list, wi

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By default, access control lists (ACLs) are supported by NFS under Red Hat Enterprise Linux. Todisable this feature, specify the no _acl option when

Causes all directories listed in /etc/expo rts to be exported by constructing a new exportlist in /etc/l ib/nfs/etab. This option effectively refreshe

Controls which TCP and UD P port mo untd (rpc. mo untd ) uses.ST AT D _P O R T = portControls which TCP and UD P port status (rpc. statd ) uses.LO C

# mount myserver:/ /mnt/#cd /mnt/exports# ls exportsfoobarOn servers that support both NFSv4 and either NFSv2 or NFSv3, both methods will work and giv

2. Ensure the package that provides the nfs-rdma service is installed and the service is enabledwith the following command:# yum i nstal l rd ma; ch

Wildcards should be used sparingly when exporting directories through NFS, as it is possible for thescope of the wildcard to encompass more systems th

Another important security feature of NFSv4 is the removal of the use of the MO UNT protocol formounting file systems. This protocol presented possib

# rpci nfo -pExamp le 9 .7. rpci nfo -p co mman d ou t p u tThe following is sample output from this command:program vers proto port service 1

Useful Websiteshttp://linux-nfs.org — The current site for developers where project status updates can be viewed.http://nfs.sourceforge.net/ — The old

Chapter 10. FS-CacheFS-Cache is a persistent local cache that can be used by file systems to take data retrieved from overthe network and cache it on

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To provide caching services, FS-Cache needs a cache back-end. A cache back-end is a storagedriver configured to provide caching services (i.e. cachefi

File systems that support functionalities required by FS-Cache cache back-end include the Red HatEnterprise Linux 6 implementations of the following f

Level 1: Server detailsLevel 2: Some mount options; security type; FSID; uniquifierLevel 3: File HandleLevel 4: Page number in fileTo avoid coherency

Opening a file from a shared file system for direct I/O will automatically bypass the cache. This isbecause this type of access must be direct to the

ImportantCulling depends on both bxxx and fxxx pairs simultaneously; they can not be treatedseparately.10.5. St at ist ical Informat ionFS-Cache also

⁠Part II. Storage AdministrationThe Storage Administration section starts with storage considerations for Red Hat Enterprise Linux 6.Instructions rega

Chapter 11. Storage Considerations During InstallationMany storage device and file system settings can only be configured at install time. Other setti

Ext3 16TB 2TB 32,000 8 Yes Chapter 5,The Ext3 FileSystemExt4 16TB 16TB ⁠Unlimited⁠8 Yes Chapter 6,The Ext4 FileSystemXFS 100TB 100TB ⁠Unlimited 8 Yes

Encrypting Block Devices Using LUKSFormatting a block device for encryption using LUKS/d m-crypt will destroy any existing formattingon that device. A

This will cause the I/O to later fail with a checksum error. This problem is common to all block device(or file system-based) buffered I/O or mmap(2)

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Chapter 12. File System CheckFilesystems may be checked for consistency, and optionally repaired, with filesystem-specificuserspace tools. These tools

NoteLater phases of consistency checking may print extra errors as it discoversinconsistencies which would have been fixed in early phases if it were

crash.If these filesystems encounter metadata inconsistencies while mounted, they will record this fact in thefilesystem superblock. If e2fsck finds t

NoteAlthough an fsck. xfs binary is present in the xfsprogs package, this is present only tosatisfy initscripts that look for an fsck. filesystem bina

6. Link count checks.7. Freemap checks.8. Superblock checks.These phases, as well as messages printed during operation, are documented in depth in

Chapter 13. PartitionsThe utility parted allows users to:View the existing partition tableChange the size of existing partitionsAdd partitions from f

rm minor-num Remove the partitionsel ect device Select a different device to configureset minor-num flag state Set the flag on a partition; state is e

hp-ufssun-ufsxfsIf a Fi l esystem of a device shows no value, this means that its file system type is unknown.The Fl ag s column lists the flags set f

# mkpart pri mary ext3 10 24 20 4 8NoteIf you use the mkpartfs command instead, the file system is created after the partition iscreated. However, pa

The first column should contain UUID = followed by the file system's UUID. The second columnshould contain the mount point for the new partition