search for: l2arc

Hello, How do you tell how much of your l2arc is populated? I''ve been looking for a while now, can''t seem to find it. Must be easy, as this blog entry shows it over time: http://blogs.sun.com/brendan/entry/l2arc_screenshots And follow up, can you tell how much of each data set is in the arc or l2arc? -- This message poste...

...e no SAS/ SATA problems). Specs: http://www.oczenterprise.com/ssd-products/deneva-2-r-sata-6g-2.5-emlc.html I want to use the 2 OCZ SSDs as mirrored intent log devices, but as the intent log needs quite a small amount of the disks (10GB?), I was wondering if I can use the rest of the disks as L2ARC? I have a few questions about this: -Is 10GB enough for a log device? -Can I partition the disks (10GB + 90 GB) and use the unused (90GB) space as L2ARC? -If I use the rest of the disks as L2ARC, do I have to mirror the L2ARC or can I just add 2 partitions (eg: 2 x 90GB = 180GB) -If I used no...

I have some questions about the choice of SSDs to use for ZIL and L2ARC. I''m trying to build an OpenSolaris iSCSI SAN out of a whitebox system, which is intended to be used as a backup SAN during storage migration, so it''s built on a tight budget. The system currently has 4GB RAM, 3GHz Core2-Quad and 8x 500GB WD REII SATA HDDs attached to an Arec...

Hi, as Richard Elling wrote earlier: "For more background, low-cost SSDs intended for the boot market are perfect candidates. Take a X-25V @ 40GB and use 15-20 GB for root and the rest for an L2ARC. For small form factor machines or machines with max capacity of 8GB of RAM (a typical home system) this can make a pleasant improvement over a HDD-only implementation." For the upcoming 2010.03 release and now testing with a b134. What is the most appropiate way to accomplish this? The caim...

Hi, When deploying ZFS in cluster environment it would be nice to be able to have some SSDs as local drives (not on SAN) and when pool switches over to the other node zfs would pick up the node''s local disk drives as L2ARC. To better clarify what I mean lets assume there is a 2-node cluster with 1sx 2540 disk array. Now lets put 4x SSDs in each node (as internal/local drives). Now lets assume one zfs pool would be created on top of a lun exported from 2540. Now 4x local SSDs could be added as L2ARC but because th...

Hello all, A few months ago I saw a statement that L2ARC writes are simplistic in nature, and I got the (mis?)understanding that some sort of ring buffer may be in use, like for ZIL. Is this true, and the only metric of write-performance important for L2ARC SSD device is the sequential write bandwidth (and IOPS)? In particular, there are some SD/MMC/CF c...

...nce, I need to block align the SSD device, but I am not sure exactly how I should to it. If I run the format -> fdisk it allows me to partition based on a cylinder, but I don''t think that is sufficient enough. Can someone tell me how they block aligned an SSD device for use in l2arc. Thanks, Geoff -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.opensolaris.org/pipermail/zfs-discuss/attachments/20100709/ecc38104/attachment.html>

...reads & writes within 10 files each file is 256M, ie, (10 * 256M = 2.5GB total Dataset Size). I have set the ARC max size to 1 GB on etc/system file In the worse case, let us assume that the whole dataset is hot, meaning my workingset size= 2.5GB My SSD flash size = 8GB and being used for L2ARC No slog is used in the pool My File system record size = 8K , meaning 2.5% of 8GB is used for L2ARC Directory in ARC. which ultimately mean that available ARC is 1024M - 204.8M = 819.2M Available ARC (Am I Right ?) Now the Question ... After running the workload for 75 minutes, I have noticed...

I''m running a mirrored pair of 2 TB SATA drives as my data storage drives on my home workstation, a Core i7-based machine with 10 GB of RAM. I recently added a sandforce-based 60 GB SSD (OCZ Vertex 2, NOT the pro version) as an L2ARC to the single mirrored pair. I''m running B134, with ZFS pool version 22, with dedup enabled. If I understand correctly, the dedup table should be in the L2ARC on the SSD, and I should have enough RAM to keep the references to that table in memory, and that this is therefore a well-performi...

Greeting ALL I understand that L2ARC is still under enhancement. Does any one know if ZFS can be upgrades to include "Persistent L2ARC", ie. L2ARC will not loose its contents after system reboot ? -- Abdullah Al-Dahlawi George Washington University Department. Of Electrical & Computer Engineering ---- Check The Fast...

Are there any drawbacks to partition a SSD in two parts and use L2ARC on one partition, and ZIL on the other? Any thoughts? -- This message posted from opensolaris.org

...isk and a ssd as a cache zpool create hdd c11t0d0p3 zpool add hdd cache c8t0d0p0 - cache device I ran an OLTP bench mark to emulate a DMBS One I ran the benchmark, the pool started create the database file on the ssd cache device ??????????? can any one explain why this happening ? is not L2ARC is used to absorb the evicted data from ARC ? why it is used this way ??? -- Abdullah Al-Dahlawi George Washington University Department. Of Electrical & Computer Engineering ---- Check The Fastest 500 Super Computers Worldwide http://www.top500.org/list/2009/11/100 -------------- next p...

Hi, Out of pure curiosity, I was wondering, what would happen if one tries to use a regular 7200RPM (or 10K) drive as slog or L2ARC (or both)? I know these are designed with SSDs in mind, and I know it''s possible to use anything you want as cache. So would ZFS benefit from it? Would it be the same? Would it slow down? I guess it would slow things down, because it would be trying to read/write from a single spindle in...

Hello everyone, I''m wondering if the following makes sense: To configure a system for high IOPS, I want to have a zpool of 15K RPM SAS drives. For high IOPS, I believe it is best to let ZFS stripe them, instead of doing a raidz1 across them. Therefore, I would like to mirror the drives for reliability. Now, I''m wondering if I can get away with using a large capacity 7200

Hi, I don''t know if it''s already been discussed here, but while thinking about using the OCZ Vertex 2 Pro SSD (which according to spec page has supercaps built in) as a shared slog and L2ARC device it stroke me that this might not be a such a good idea. Because this SSD is MLC based, write cycles are an issue here, though I can''t find any number in their spec. Why do I think it might be a bad idea: L2ARC is quite static in comparison with ZIL and L2ARC takes all the place it c...

We are looking into the possibility of adding a dedicated ZIL and/or L2ARC devices to our pool. We are looking into getting 4 ? 32GB Intel X25-E SSD drives. Would this be a good solution to slow write speeds? We are currently sharing out different slices of the pool to windows servers using comstar and fibrechannel. We are currently getting around 300MB/sec performance w...

What would the performance impact be of splitting up a 64 GB SSD into four partitions of 16 GB each versus having the entire SSD dedicated to each pool? Scenario A: 2 TB Mirror w/ 16 GB read cache partition 2 TB Mirror w/ 16 GB read cache partition 2 TB Mirror w/ 16 GB read cache partition 2 TB Mirror w/ 16 GB read cache partition versus Scenario B: 2 TB Mirror w/ 64 GB read cache SSD 2 TB

...t, iostat, vmstat, and friends. The current usage is: Usage: arcstat [-hvx] [-f fields] [-o file] [interval [count]] Field definitions are as follows: mtxmis : mutex_miss per second arcsz : ARC size mrug : MRU ghost list hits per second l2hit% : L2ARC access hit percentage mh% : Metadata hit percentage l2miss% : L2ARC access miss percentage read : Total ARC accesses per second l2hsz : L2ARC header size c : ARC target size mfug : MFU ghost list hits per second miss : ARC...

Hi. I can''t reach Brendan Gregg with this question (user unknown, he doesn''t work for Oracle anymore?), so I''m sending it here: FreeBSD users report much better performance and lower disk and CPU load when L2ARC also holds prefetched data (l2arc_noprefetch = B_FALSE). I was wondering what was the reason to avoid storing prefetched data on L2ARC vdevs by default. -- Pawel Jakub Dawidek http://www.wheelsystems.com pjd at FreeBSD.org http://www.FreeBSD.org Fre...

Will btrfs in the future implement a read cache like zfs has with l2arc, following it''s hybrid storage concept. This would take away the hassle of choosing what and what not should be on your SSD, it would speed up the things you do most. And not what you did a lot a week ago. It should be persistent between boots so your boot sequence would benefit too. I...