テープドライブがとても遅いのはなぜですか？
使用済みのQuantumUltrium LTO-4テープドライブを購入し、HP Smart Array P400 SASコントローラーのHPProLiantN54lに接続しました。オペレーティングシステムとしてFreeBSD11を使用しています。
これで、テープを挿入して、Baculaのbtapeコマンドのベンチマークを実行しました。
$ btape /dev/nsa0
Tape block granularity is 1024 bytes.
btape: butil.c:291-0 Using device: "/dev/nsa0" for writing.
btape: btape.c:471-0 open device "LTO-4" (/dev/nsa0): OK
*rewind
btape: btape.c:576-0 Rewound "LTO-4" (/dev/nsa0)
*speed
btape: btape.c:1055-0 Test with zero data, should give the maximum throughput.
btape: btape.c:904-0 Begin writing 3 files of 1.073 GB with raw blocks of 64512 bytes.
++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 2.182 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 4.511 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 1.835 MB/s
btape: btape.c:379-0 Total Volume bytes=3.221 GB. Total Write rate = 2.449 MB/s
これ（および他のいくつかのテスト）では、書き込み速度が約2 MB/sであることが確認されていますが、これは不当に遅いです。なぜそうなのですか？書き込み速度を期待される速度（100 MB/sなど）に上げるにはどうすればよいですか？
編集
コントローラに問題があるようです。再起動後、PCIエラーが多数発生し、速度が低下してクロールするまで、しばらくの間、高速でデータを転送することができました。
ciss0: *** PCI-E LL correctable errors, count=10546, LLErrStatus=0x80000004
ciss0: *** PCI-E LL correctable errors, count=20570, LLErrStatus=0x80000004
ciss0: *** PCI-E LL correctable errors, count=30995, LLErrStatus=0x80000004
ciss0: *** PCI-E LL correctable errors, count=41101, LLErrStatus=0x80000004
ciss0: *** PCI-E LL correctable errors, count=51400, LLErrStatus=0x80000004
ciss0: *** PCI-E LL correctable errors, count=61729, LLErrStatus=0x80000004
おそらく、カードが正しく装着されていないか、そのようなものです。
HP SmartArray P400 SASコントローラーをLSI3041E SASコントローラーに交換しました。これでパフォーマンスの問題が解決し、高速で快適にバックアップできるようになりました（実際には約70MB/sに達します）。以下に、以前に使用したのと同じパフォーマンステストからの出力を示します。
$ btape /dev/nsa0
Tape block granularity is 1024 bytes.
btape: butil.c:291-0 Using device: "/dev/nsa0" for writing.
btape: btape.c:471-0 open device "LTO-4" (/dev/nsa0): OK
*rewind
btape: btape.c:576-0 Rewound "LTO-4" (/dev/nsa0)
*speed
btape: btape.c:1055-0 Test with zero data, should give the maximum throughput.
btape: btape.c:904-0 Begin writing 3 files of 1.073 GB with raw blocks of 64512 bytes.
++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 71.58 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 119.3 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 134.2 MB/s
btape: btape.c:379-0 Total Volume bytes=3.221 GB. Total Write rate = 100.6 MB/s
btape: btape.c:904-0 Begin writing 3 files of 2.147 GB with raw blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 143.1 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 153.3 MB/s
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 143.1 MB/s
btape: btape.c:379-0 Total Volume bytes=6.442 GB. Total Write rate = 146.4 MB/s
btape: btape.c:904-0 Begin writing 3 files of 4.294 GB with raw blocks of 64512 bytes.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 165.1 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 165.1 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 165.1 MB/s
btape: btape.c:379-0 Total Volume bytes=12.88 GB. Total Write rate = 165.1 MB/s
btape: btape.c:1067-0 Test with random data, should give the minimum throughput.
btape: btape.c:904-0 Begin writing 3 files of 1.073 GB with raw blocks of 64512 bytes.
++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 53.69 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 51.13 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 53.69 MB/s
btape: btape.c:379-0 Total Volume bytes=3.221 GB. Total Write rate = 52.80 MB/s
btape: btape.c:904-0 Begin writing 3 files of 2.147 GB with raw blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 59.65 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 58.04 MB/s
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 58.04 MB/s
btape: btape.c:379-0 Total Volume bytes=6.442 GB. Total Write rate = 58.56 MB/s
btape: btape.c:904-0 Begin writing 3 files of 4.294 GB with raw blocks of 64512 bytes.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 60.49 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 70.41 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 69.27 MB/s
btape: btape.c:379-0 Total Volume bytes=12.88 GB. Total Write rate = 66.41 MB/s
btape: btape.c:1081-0 Test with zero data and bacula block structure.
btape: btape.c:959-0 Begin writing 3 files of 1.073 GB with blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 71.58 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 76.70 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 71.58 MB/s
btape: btape.c:379-0 Total Volume bytes=3.221 GB. Total Write rate = 73.21 MB/s
btape: btape.c:959-0 Begin writing 3 files of 2.147 GB with blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 93.37 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 85.90 MB/s
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 89.48 MB/s
btape: btape.c:379-0 Total Volume bytes=6.442 GB. Total Write rate = 89.48 MB/s
btape: btape.c:959-0 Begin writing 3 files of 4.294 GB with blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 97.61 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 99.88 MB/s
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 97.61 MB/s
btape: btape.c:379-0 Total Volume bytes=12.88 GB. Total Write rate = 98.35 MB/s
btape: btape.c:1093-0 Test with random data, should give the minimum throughput.
btape: btape.c:959-0 Begin writing 3 files of 1.073 GB with blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 41.30 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 39.77 MB/s
+++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=1.073 GB. Write rate = 41.30 MB/s
btape: btape.c:379-0 Total Volume bytes=3.221 GB. Total Write rate = 40.77 MB/s
btape: btape.c:959-0 Begin writing 3 files of 2.147 GB with blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 45.69 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 44.74 MB/s
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=2.147 GB. Write rate = 44.74 MB/s
btape: btape.c:379-0 Total Volume bytes=6.442 GB. Total Write rate = 45.05 MB/s
btape: btape.c:959-0 Begin writing 3 files of 4.294 GB with blocks of 64512 bytes.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 45.69 MB/s
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 49.94 MB/s
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
btape: btape.c:606-0 Wrote 1 EOF to "LTO-4" (/dev/nsa0)
btape: btape.c:405-0 Volume bytes=4.295 GB. Write rate = 51.13 MB/s
btape: btape.c:379-0 Total Volume bytes=12.88 GB. Total Write rate = 48.80 MB/s
*quit
私が実行した次のテストから明らかなように、このSASコントローラーの行は一般にテープドライブを好まない」と確信しています。
- SmartArray P400を同じ種類の別のコントローラーと交換しましたが、結果は
PCI-E LL correctable errors。 - ケーブルを別のケーブルに交換しました。同じ結果です。
- SmartArray P400カードにハードディスクドライブを接続しましたが、問題なく動作しました。
最小および最大の読み取りおよび書き込み速度は、ドライブによって異なります。
LTO-4の最大非圧縮速度（120 MBps）。
Quantum LTO-4 HHテープドライブは、最大576GB/hrの圧縮転送速度を備えています。2：1の圧縮を想定しています。
[。ドライブ仕様から：
データレートの一致範囲：ネイティブ33〜80MB /秒
したがって、100 MB/sを取得することはありません
編集：
について読む Baculaでテープドライブをテストする 。
bacula-sd.confファイルを設定し、Bacula（ストレージデーモン）が実行されていないこと、またはテストに使用するドライブをアンマウントしていることを確認する必要があります。