Search results for query: padding overhead

  1. Dunuin

    Disk Performance Probleme bei KVM Server mit ZFS

    Eine Sache die man tun kann ist z.B. die volblocksize für seine Workload anzupassen. Gerade wenn man ein Raidz1/2/3 benutzt sollte man das immer tun, da man sonst massiv Padding-Overhead hat. Siehe hier für raidz1/2/3...
  2. Dunuin

    RAIDZ Calculator

    Padding Overhead hast du nur bei Raidz1/2/3 glaube ich. 4x 2TB SSDs im Raid10 (bei ZFS "Striped Mirror" genannt) hättest du: (8 TB Rohkapazität - 4 TB Parität) * 80% = 3,2 TB nutzbar Und bei 6x 2 TB SSDs im Raid10 wären es 4,8 TB. HDDs würde ich heute nicht mehr als Storage für VMs/LXCs...
  3. A

    RAIDZ Calculator

    ...habe würde die Berechnung dann folgendermassen aussehen. 4 SSDs mit jeweils 2 TB : 8 TB Rohkapazität - 2 TB Parität -4 TB Padding Overhead * 80% = 1,6 TB Dann komme ich mit 4 SSDs nicht wirklich so weit, oder ? Auf dem jetzigen Host habe ich 6 VMs mit jeweils 300 MB virtual hard disks am...
  4. Dunuin

    RAIDZ Calculator

    Du solltest dich mal mit der Volblocksize und Padding Overhead bei Raidz beschäftigen: https://www.delphix.com/blog/delphix-engineering/zfs-raidz-stripe-width-or-how-i-learned-stop-worrying-and-love-raidz Kurz: Nimmst du keine recht hohe Volblocksize, was die Performance von DBs wie MySQL und...
  5. Dunuin

    ZFS noob question

    ...space by using defined sizes. Also keep in mind that 20% of a ZFS pool should always be kept free, so of your pool only 12.8TB or 11.64 TiB are actually usable. In in case you are working with zvols and don't increase your volblocksize you will loose additional capacity due to padding overhead.
  6. Dunuin

    [SOLVED] RaidZ2 terrbile high IO delay

    Don't choose a too small blocksize or you get alot of padding overhead: https://www.delphix.com/blog/delphix-engineering/zfs-raidz-stripe-width-or-how-i-learned-stop-worrying-and-love-raidz And don't fill your pool more than 80% or it will get slow too. So 20% should always be kept free.
  7. Dunuin

    Unter "Übersicht" auch den Füllstand der HDDs anzeigen?

    ...das ist auch nicht gerage aussagekräftig. Sagen wir z.B. die Volblocksize ist nicht ideal und man hat ordentlich (sagen wir +50%) Padding Overhead. Wenn das Zvol dann 500GB vom Pool belegen würde, dann wäre das 1TB Zvol nicht zu 50% sondern erst zu 33% voll, weil 1TB an Daten wegen dem...
  8. Dunuin

    Newb, confused at raidz2 available space

    Read this to understand volblocksize and padding overhead: https://www.delphix.com/blog/delphix-engineering/zfs-raidz-stripe-width-or-how-i-learned-stop-worrying-and-love-raidz I guess you kept the default 8K volblocksize and with a 4 disk raidz2 you will loose 66,6% of the raw capacity to...
  9. Dunuin

    Newbie question on ZFS - using multiple devices as a single logical unit

    ...be used by snapshots so you maybe just got 400 or 600GB for actual data. And in case of raidz with zvols you also might have some padding overhead wasting even more space. Compression usually improves performance, atleast with LZ4 compression, because most of the time the CPU can compress...
  10. Dunuin

    Reduce ram requirement/usage due to having ZFS

    ...increased your volblocksize so you are loosing 50% of your raw capacity. 25% loss of the raw capacity to parity and 25% loss to padding overhead. Also keep in mind that a zfs pool should not be filled up more than 80%, because otherwise it will get slow and fragment faster. So actually you...
  11. Dunuin

    Installation: root + swap on SSD, data on ZFS

    ...with zvols don't forget to increase the volblocksize before creating your first VM. Otherwise you will waste alot of capacity due to padding overhead. With a 3 disks in raidz1 you probably need to increase the default volblocksize from 8K to 16K (Datacenter -> Storage -> YourZFSPool -> Edit...
  12. Dunuin

    Zfs summary usage - wrong?!

    And don't forget the overhead. Especially when using a raidz1/2/3 you often get alot of padding overhead. Lets say you write 1TB to a zvol and that zvol will then need 1.66 TB on the pool. That additional 0.66 TB come from the padding overhead when you use raidz1/2/3 without increasing the...
  13. Dunuin

    [SOLVED] zfs storage full but i don't understand why

    The problem should be padding overhead caused by using raidz with a too small volblocksize. Read this: https://www.delphix.com/blog/delphix-engineering/zfs-raidz-stripe-width-or-how-i-learned-stop-worrying-and-love-raidz You probably want atleast 8 times your ashift as volblocksize to only...
  14. Dunuin

    VM Disk not adding up in ZFS gui

    ...With a volblocksize of 16K you will loose 33% and with a volblocksize of the default 8K even 50% of your raw capacity. Padding overhead only effects blockdevices and not file systems. VMs use zvols (blockdevices) and LXCs use datasets (file systems) so only VMs should be affected by padding...
  15. Dunuin

    VM Disk not adding up in ZFS gui

    ...SCSI that supports TRIM and not IDE or virtio block. Make sure your virtual disk got the discard checkbox checked. 3.) Raidz with padding overhead because ZFS rookies don't get that you need to increase the volblocksize when using raidz1/2/3 or otherwise you will waste alot of space to...
  16. Dunuin

    Adding new disks to Raidz

    ...is still using the old data-to-parity-ratio. And if you run VMs that pool you might need to recreate the guests as well as with more disks you possibly need to increase your volblocksize so you don't loose too much capacity to padding overhead. So adding new disks can still cause alot of work.
  17. Dunuin

    VMs disk growing beyond the allocated size

    ...zvols of that VM and create new ones using the 16K volblocksize and fill it with the data of the backups. Much of that 30T is padding overhead. After increasing the volblocksize to something like 16K it should only use something like 16T or 17T to store those 15T. Jup, so everything will...
  18. I

    VMs disk growing beyond the allocated size

    My RAIDZ2 consists of 8 disks + logs and cache: root@san01[~]# zpool status pool01 pool: pool01 state: ONLINE scan: scrub repaired 0B in 6 days 06:19:08 with 0 errors on Fri Jan 21 06:28:27 2022 config: NAME STATE READ WRITE CKSUM...
  19. Dunuin

    VMs disk growing beyond the allocated size

    Whats your zpool status pool01 or how much disks your raidz2 consists of? There is a good explanation about padding overhead and volblocksize: https://www.delphix.com/blog/delphix-engineering/zfs-raidz-stripe-width-or-how-i-learned-stop-worrying-and-love-raidz With a 4K volblocksize you will...
  20. I

    VMs disk growing beyond the allocated size

    ...zfs get volblocksize pool01/vm-100-disk-1 NAME PROPERTY VALUE SOURCE pool01/vm-100-disk-1 volblocksize 4K - I don't know about this, I will do a research on padding overhead on a ZFS volblocksize. If you have any suggestion on this matter I would appreciate.