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Questions tagged [zfs-l2arc]

22 questions
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3 answers

ZFS - Impact of L2ARC cache device failure (Nexenta)

I have an HP ProLiant DL380 G7 server running as a NexentaStor storage unit. The server has 36GB RAM, 2 LSI 9211-8i SAS controllers (no SAS expanders), 2 SAS system drives, 12 SAS data drives, a hot-spare disk, an Intel X25-M L2ARC cache and a…
ewwhite
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1 answer

Offline uncorrectable sectors in SSDs being used for ZFS L2ARC?

I have two enterprise-grade SSDs that I've been using for L2ARC in an OpenZFS pool for a few years. Workflow during this time has been fairly heavy, with lots of reads and writes, serving up video to clients for video post-production. Recently, got…
user260467
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2 answers

What's in my ZFS ARC and L2ARC caches?

I have a simple ZFS setup at home, four disks mirrored, 8GB ram and 120GB Intel X25-M SSD for L2ARC. I ran zpool add poolname cache cXtXdX then generated load and eagerly tracked the warming process by running zpool iostat -v mypool. A few hours…
notpeter
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1 answer

Solaris ZFS volumes: workload not hitting L2ARC

I've set up a Solaris Express 11 machine with some reasonably fast HDDs behind a RAID controller, set the device up as a zpool with compression enabled and added a mirrored log and 2 caching devices to it. The datasets are exposed as FC targets for…
the-wabbit
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5
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2 answers

Priming a ZFS L2ARC cache on Solaris 11.3

Is there a good way to prime a ZFS L2ARC cache on Solaris 11.3? The L2ARC is designed to ignore blocks that have been read sequentially from a file. This makes sense for ongoing operation but makes it hard to prime the cache for initial warm-up or…
Tom Shaw
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4
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2 answers

size the write cache ZFS

I would like to add a write cache to my Nexenta. I thought about using 2 SSDs in mirror with a third disc in spare. The problem is: How do I calculate the size of my array to maximize the investment (of course I do not want to spend much money in…
CSG
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ZFS L2ARC at no expense

I recently upgraded my workstation's SSDs, so now I have 2x256GB SSDs laying around. I am considering to use them as L2ARC disks on my NAS. However my NAS has only 12GB of RAM and 8TB worth of disk space (5x2TB in RAID-Z). I've read that having…
oierlauzi
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2 answers

Is ZFS L2ARC required if primary data is already on SSD?

I'm trying to tune ZFS on Linux for my workload (Postgres and a fileserver on the same physical machine [1]), and wanted to understand if I really need L2ARC, or not. If the information given at…
Saurabh Nanda
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3
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1 answer

Tracing what blocks go through L2ARC in ZFS on Solaris using dtrace

My colleague and myself are trying to trace the reads/writes to the L2ARC in OpenZFS. We want the block offsets, IO type (read/write) and the device-ids of the requests. Note that we don't want the offset in the L2ARC device but we want the…
trauzti
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zfs: flush cache without exporting

For testing I need zfs' cache to be cold. I can flush caching from the pool by removing the cache disks, exporting and importing the pool. This gives the effect I want. But would really like not to export the pool. Is there a less drastic way to…
Ole Tange
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How should I use the new Optum drive?

I have a zpool consisting of 7 2TB HDDs of different vintage in a raidz setup. Currently, there is neither ZIL nor L2ARC device configured. The server has 12GB of RAM and no swap. The different filesystems on the pool include /var/spool/imap and…
Mikhail T.
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1 answer

In my ZFS box, why is my cache devices leaving a bunch of free space?

I have a ZFS system serving many VMs. In it, we installed 12x4TB SAS disks and configured them in a mirror. We added two PCI-E SSDs (Samsung 960s with 512GB each), but they are each consumed to just over 50% rather than caching all the data they…
user1955162
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4 answers

Will a SSD cache increase Native ZFS performance for me?

I'm using Ubuntu 11.10 Desktop x64 with Native ZFS using a mirrored pool of 2x2 TB 6.0 Gbps hard drives. My issue is that I'm only getting about 30 Mb/s read/write at any time, I would think my system could perform faster. There are some…
knorrhane
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Diagnosize ZFS cache needs

I have a peculiar load on a machine that is limited by disk IO, mostly reads. The bulk of the IO happens on slow network attached disk that are formated with ZFS. Using iostat I can clearly see that the use of those disk is at around 100%, hence, at…
Siscia
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1 answer

ZFS on Linux and KVM: NUMA nodes for host

I am interested in using KVM images on zvols under ZFS on Linux, on a multi-socket system. I am wondering how I should pin NUMA nodes so as to maximize the benefits of ZFS ARC cache for all KVM images on the system. Obviously, I should pin each VM…
Stonecraft
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