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Tag Archives: SLOG

Crucial m550 128GB as ZIL/SLOG (the ZIL really does limit your performance)


I got my hands on an m550 128GB drive (for around $75 with the recent pre-Thanksgiving/pre-Christmas discounts). Here are some comparisons between my old ZIL (the m500 128GB) and the new one: ZIL Throughput (sustained) MB/s none 195.6 m500 128GB 124.0 m550 128GB 265.9 Here are some snippets of zpool isotat output: No ZIL


Crucial m500 120GB as a ZFS slog


I re-did my benchmarks of my ZFS ZIL using a Crucial m500. The main reason I got this drive is that it has power-loss protection. And, it’s speeds are adequate to keep up with my gigabit Ethernet samba server. Here are the results. My first run was decent, but not stellar:

I didn’t do […]

More ZIL/SLOG comparisons


Suspicious of my previous tests using iozone, I wrote a small program (that follows) to measure synchronous write speed. I tested this with and without an SLOG device, and then used a really fast Plextor M5 Pro 256GB SSD as the SLOG. I wanted to make sure that something could achieve the fast SLOG speed […]

SLOG tests on a 32GB Kingston SSD with iozone


This is a follow-up on my previous post. I ran iozone both with and without the [ccie]-e[/ccie] flag. This flag includes a sync/flush in the speed calculations. This flush should tell ZFS to commit the in-process data to disk, thus flushing it to the SLOG device (or to the on-disk ZIL). I ran 4 tests: […]

ZFS slog (ZIL) considerations


Running List of Alternatives 2015-08-11 It looks from this Anandtech article that the m550 does not have as strong power-loss protection as I originally thought. It protects the “lower pages” (least-significant bits) from corruption between page writes. But, it does not protect the DRAM buffer from losing data. 2014-07-07 The Transcend MTS600 line is capable […]