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CT storage backends

682 bytes added, 13:05, 6 June 2016
Reorganization, deduplication, +LVM +ZFS
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= Comparison tables =
<translate>=== Solidity in front of failures and security ===
<!--T:1-->
{| class="wikitable sortable" style="text-align: center;"
! Feature
! OVZ Ploop! SIMFSOVZ SimFS (ext4)! LVM (ext4)! ZFS (~simfs)
|-
|'''MaturityI/O isolation'''|Since 2012{{Yes|Good}}|{{No|Bad}}: Some bug could be exploited to escape CT and access HN file system}}: [https://bugs.openvz.org/browse/OVZ-6296 CVE-2015-2925], [http://www.openwall.com/lists/oss-security/2014/06/24/16 CVE-2014-3519]|{{Yes|Good}}|Since 2005 (?){{Yes|Good}}
|-
|'''Maximum disk spaceReliability'''|Limited{{No|Low}}: big amount of files produce ext4 corruption so often|Medium:<ref>[[Ploop/Limits]]</ref> ploop v1 - 2 Tbfsck, ploop v2 - 4 Tbpower loss and HW Raid without cache can kill whole data|High: LVM metadata can be corrupted completely|Limited by ext4 filesystem{{Yes|Excellent}}: no write hole, checksumming and COW
|-
|'''Disk space overheadRisk to be using filesystem over filesystem'''|{{No|Yes}}, up to 20% for allocated ext4 metadata|{{Yes|No}}|{{Yes|No}}|?
|-
|'''SpeedEffect of HN filesystem corruption at /vz'''|Fast{{Yes|No effect}}|{{No|Same FS}}|?|Fast only with small amount of containers per node?
|-
|'''IMaturity in O/O isolationVZ'''|Good{{No|Since 2012}}|{{Yes|Since ~2005}}|Bad, "no inodes" issues (when file system journal is bottleneck){{Yes|Since 1998}}|{{No|Since 2014}}
|-
|'''Need for run external tools for compaction VE imagesIncremental backup support on filesystem level'''|{{Yes}}, you should vzctl compact every few days for saving your disk spacethrough snapshots|{{No}}
|{{No}}
|{{Yes}}
|-
|}
 
=== Performance and design features ===
<!--T:1-->
{| class="wikitable sortable" style="text-align: center;"
! Feature
! OVZ Ploop
! OVZ SimFS (ext4)
! LVM (ext4)
! ZFS (~simfs)
|-
|'''Maximum container volume space'''
|4 TiB <ref>[[Ploop/Limits]]</ref>
|1 EiB
|1 EiB
|256 ZiB
|-
|'''Disk Wasted space overcommit (provide more space for containers than available on server now)due to architecture'''|{{No|up to 20%}}|{{Yes|No}}|{{YesNo|up to 20%}}|?
|-
|'''ReliabilityDisk i/o speed'''|Low: big Fast in any case|Very fast with small amount of files produce ext4 corruption so oftencontainers|Fast in any case|High: fsck, power loss and HW Raid without cache can kill whole dataFast in any case
|-
|'''Access to private area from host Disk space overcommit (provide more space for containers than available on server now)'''
|{{Yes}}
|{{Yes}}
|-|'''Fear to use filesystem over filesystem'''No
|{{Yes}}
|{{No}}
|-
|'''Live backup is easy and consistent'''
|{{Yes}}<ref name="ploop backup">[http://openvz.livejournal.com/44508.html ploop snapshots and backups]</ref><ref>[[Ploop/Backup]]</ref>, fast block level backup
|{{No}} (in case of big number of files )
|-
|'''Incremental backup support on filesystem level'''
|{{Yes}} (snapshots)
|{{No}}
|-
|'''Different containers may use file systems of different types and properties'''
|{{Yes}}
|{{No}}
|Yes
|No
|-
|'''Live migration is reliable and efficientSecond level quotes in Linux (inside container)'''
|{{Yes}}
|{{No}}, when apps rely on files i-node numbers being constant (which is normally the case), those apps are not surviving the migration
|-
|'''Continue failed CT migration'''
|{{Yes}}, in [https://lists.openvz.org/pipermail/users/2015-July/006335.html vzctl] from OpenVZ -stable
|{{Yes}}, option "--keep-dst"
|-
|'''Second level quotes in Linux (inside container)'''
|{{Yes}}
|{{Yes}}
|{{No|Not implemented}}
|-
|'''[Potential] support for QCOW2 and other image formats'''
|{{Yes}}
|{{No}}
|{{No}}
|No
|-
|} === Administrator operations ===<!--T:1-->{| class="wikitable sortable" style="text-align: center;"! Feature! OVZ Ploop! OVZ SimFS (ext4)! LVM (ext4)! ZFS (~simfs)|-|'''External compaction for container volumes'''|{{No|Needed}} for saving HN space|{{Yes|No}}|{{No problems with fs corruption on /vz parition|Not available}}|{{Yes|Not required}}|-|'''Access to private area from host'''
|{{Yes}}
|{{Yes}}|?|?|-|'''Live backup'''|{{Yes|Easy, fast and consistent}}<ref name="ploop backup">[http://openvz.livejournal.com/44508.html ploop snapshots and backups]</ref><ref>[[Ploop/Backup]]</ref>|{{No|Easy, slow, and sometimes inconsistent}} in case some application depends on inode IDs|{{No|Fast}}|{{Yes|Fast}}theoretically
|-
|'''Snapshot support'''
|{{Yes}}<ref name="ploop backup">[http://openvz.livejournal.com/44508.html ploop snapshots and backups]</ref>
|{{No}}theoretically, (because there is a lot of much/small files that need to be copied)|-|'''Better security'''{{Yes}}
|{{Yes}}
|{{No}} (bugs can be exploited to escape the simfs and let container access the host file system: [https://bugs.openvz.org/browse/OVZ-6296 CVE-2015-2925], [http://www.openwall.com/lists/oss-security/2014/06/24/16 CVE-2014-3519], CVE-2015-6927)
|-
|'''Shared storage support (Virtuozzo storage, NFS)Live migration'''|{{Yes|Reliable and fast}}|{{No|Not reliable and slow}}, if some application depends on inode IDs|{{No|Not implemented}}|{{Yes|Fast}}theoretically
|-
|''' Disk space footprintContinue failed CT migration'''|{{Yes}}, in [https://lists.openvz.org/pipermail/users/2015-July/006335.html vzctl] from OpenVZ -stable|{{Yes}}, option "--keep-dst"|{{No|Not implemented}}|?
|-
|}
 
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[[Category: Storage]]
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