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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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6
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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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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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4
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1 answer

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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0 answers

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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1 answer

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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1 answer

ZFS l2arc does not warm up

My setup has 256 GB of RAM, of which 200 GB are dedicated to arc, and 2 SSDs for l2arc. It's being up since several days and steadily serving files to many clients, yet it seems that the l2arc is still not warmed up properly. The cache report of…
Nicola Mori
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1
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1 answer

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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